Introduction to Chemistry
663 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is chemistry mainly concerned with?

  • Studying the behavior of matter (correct)
  • Understanding the universe
  • Describing physical phenomena
  • Classifying materials

    • What is meant by the term 'matter' in chemistry?

  • Only liquids and gases
  • Only the physical world around us
  • All substances and materials in the universe (correct)
  • Only solid substances

    • What are the two main aspects of chemistry?

  • Classifying and naming compounds
  • Understanding changes and existence of materials (correct)
  • Measuring and weighing substances
  • Describing and analyzing materials

    • What is a key characteristic of matter?

    <p>Has mass</p> Signup and view all the answers

    Why is the small-sized brick lighter than the big-sized brick?

    <p>It contains less matter</p> Signup and view all the answers

    What happens when two trucks try to cross each other in a narrow lane?

    <p>They will collide</p> Signup and view all the answers

    What is the property of matter that causes it to remain at rest or in motion?

    <p>Inertia</p> Signup and view all the answers

    What will happen to a football placed in the center of a playground?

    <p>It will remain there unless disturbed by an external force</p> Signup and view all the answers

    What is the main difference between mass and weight?

    <p>Mass is the amount of matter, while weight is the force of gravity</p> Signup and view all the answers

    Why do two stools cannot occupy the same space at the same time?

    <p>Because matter occupies space</p> Signup and view all the answers

    What is the primary focus of chemistry?

    <p>The behavior and properties of matter</p> Signup and view all the answers

    What is a fundamental characteristic of all matter?

    <p>It has mass</p> Signup and view all the answers

    What happens when an external force is applied to an object at rest?

    <p>It is disturbed from its position</p> Signup and view all the answers

    Why do two objects of different sizes occupy different amounts of space?

    <p>The smaller object has less mass</p> Signup and view all the answers

    What is the term for the amount of matter in an object?

    <p>Mass</p> Signup and view all the answers

    What is the property of matter that causes it to resist changes in motion?

    <p>Inertia</p> Signup and view all the answers

    How do we know that air is matter?

    <p>Because it has mass</p> Signup and view all the answers

    What is the result of two objects trying to occupy the same space?

    <p>They collide</p> Signup and view all the answers

    What is the primary way that matter behaves?

    <p>It maintains its state of motion</p> Signup and view all the answers

    What is the relationship between the amount of matter in an object and its mass?

    <p>The amount of matter determines the mass</p> Signup and view all the answers

    What is the force that pulls objects towards the Earth's surface?

    <p>Gravity</p> Signup and view all the answers

    According to the law of conservation of mass, what remains the same during physical and chemical changes?

    <p>Total mass of the matter</p> Signup and view all the answers

    What is the characteristic of matter that determines its physical behavior?

    <p>Movement or motion</p> Signup and view all the answers

    What is the evidence that supports the kinetic theory of matter?

    <p>The movement of pollen grains in water</p> Signup and view all the answers

    What is not considered as matter?

    <p>Heat or light</p> Signup and view all the answers

    What is the origin of the word 'kinetic'?

    <p>Greek word 'Kinos' meaning to move</p> Signup and view all the answers

    Why do fruits always fall downwards from the trees?

    <p>Because of the force of attraction exerted by the Earth</p> Signup and view all the answers

    What is the result of heating tin metal in a flask?

    <p>It is converted into tin oxide</p> Signup and view all the answers

    Why do solids, liquids, and gases have different properties?

    <p>Because of their different movements</p> Signup and view all the answers

    What is the characteristic of matter that makes it impossible to be destroyed?

    <p>It cannot be destroyed or created</p> Signup and view all the answers

    What is the force that attracts objects towards the Earth's surface?

    <p>Gravity</p> Signup and view all the answers

    What is the term for the amount of matter in an object?

    <p>Mass</p> Signup and view all the answers

    What is the characteristic of matter that determines its physical behavior?

    <p>Motion</p> Signup and view all the answers

    What is the result of heating tin metal in a flask?

    <p>Its weight remains unchanged</p> Signup and view all the answers

    What is the origin of the word 'kinetic'?

    <p>From the Greek word 'Kinos' meaning to move</p> Signup and view all the answers

    What is the evidence that supports the kinetic theory of matter?

    <p>Movement of pollen grains in water</p> Signup and view all the answers

    What is not considered as matter?

    <p>All of the above</p> Signup and view all the answers

    What is the law that states that matter cannot be created or destroyed?

    <p>Law of Conservation of Mass</p> Signup and view all the answers

    What is the reason why fruits always fall downwards from the trees?

    <p>Gravity</p> Signup and view all the answers

    What is the characteristic of particles of matter that determines their physical properties?

    <p>Motion</p> Signup and view all the answers

    What is the term for the zig-zag movement of small particles suspended in a liquid or gas?

    <p>Brownian motion</p> Signup and view all the answers

    What is the result of an increase in kinetic energy of particles of matter?

    <p>All of the above</p> Signup and view all the answers

    What is the main conclusion that can be drawn from the existence of Brownian motion?

    <p>Matter is made up of tiny particles</p> Signup and view all the answers

    What is the term for the theory that describes matter as consisting of atoms, molecules, or ions in constant motion?

    <p>Kinetic theory of matter</p> Signup and view all the answers

    What is a characteristic of particles of matter in a solid state?

    <p>They vibrate about their average position</p> Signup and view all the answers

    What is the force that exists between particles of matter in a liquid state?

    <p>Intermolecular force</p> Signup and view all the answers

    What is the result of particles being in a state of random continuous motion?

    <p>They gain kinetic energy</p> Signup and view all the answers

    What is the characteristic of particles of matter that determines their physical behavior?

    <p>Motion</p> Signup and view all the answers

    What is the main postulate of the kinetic theory of matter?

    <p>Matter consists of molecules</p> Signup and view all the answers

    What is the direction of motion of particles in a gas?

    <p>Random and zig-zag</p> Signup and view all the answers

    What is the outcome of the collisions between particles in a given substance?

    <p>The total energy of the particles remains the same.</p> Signup and view all the answers

    What is the force that causes the movement of particles in a given substance?

    <p>Intermolecular force</p> Signup and view all the answers

    What would happen to the particles if they did not collide elastically?

    <p>They would come to rest.</p> Signup and view all the answers

    What is the purpose of the starch iodide paper in the experiment?

    <p>To detect the presence of iodine particles.</p> Signup and view all the answers

    What does the diffusion of iodine particles indicate?

    <p>The particles are mobile.</p> Signup and view all the answers

    What is the observation that suggests the particles are mobile?

    <p>The starch iodide paper turns blue when brought near the test tube.</p> Signup and view all the answers

    What is the significance of the intermolecular spaces in a given substance?

    <p>It determines the magnitude of the intermolecular force.</p> Signup and view all the answers

    What is the result of the experiment with the iodine and starch iodide paper?

    <p>The particles are found to be mobile.</p> Signup and view all the answers

    What is the characteristic of the collisions between particles in a given substance?

    <p>They are elastic.</p> Signup and view all the answers

    What is the conclusion that can be drawn from the experiment with the iodine and starch iodide paper?

    <p>Particles of matter are always mobile.</p> Signup and view all the answers

    What is observed when a starch iodide paper is brought near the mouth of the test tube containing iodine?

    <p>The starch iodide paper becomes blue.</p> Signup and view all the answers

    Why do salts get dissolved in water easily even when not externally stirred?

    <p>Due to the kinetic molecular theory of matter.</p> Signup and view all the answers

    What determines the physical behavior of particles of matter in different states?

    <p>All of the above.</p> Signup and view all the answers

    What is the characteristic of particles in a solid state?

    <p>They are closely packed and have fixed positions.</p> Signup and view all the answers

    Why do solids have a definite shape and volume?

    <p>Due to their strong intermolecular forces.</p> Signup and view all the answers

    What is the characteristic of particles in a liquid state?

    <p>They are able to move past each other freely.</p> Signup and view all the answers

    Why do solids have high density?

    <p>Due to their closely packed particles.</p> Signup and view all the answers

    What is the characteristic of particles in a gas state?

    <p>They are able to move freely and have high energy.</p> Signup and view all the answers

    What is the result of the diffusion of iodine particles in the test tube?

    <p>The iodine particles spread throughout the test tube.</p> Signup and view all the answers

    What is the evidence that supports the kinetic theory of matter?

    <p>The experiment with iodine particles in a test tube.</p> Signup and view all the answers

    What is the main reason why salt dissolves easily in water?

    <p>Because of the kinetic energy of water molecules</p> Signup and view all the answers

    What is the characteristic of particles in a solid state?

    <p>They are closely packed and have fixed positions</p> Signup and view all the answers

    What happens to the iodine particles in the experiment with the starch iodide paper?

    <p>They spread throughout the test tube</p> Signup and view all the answers

    What is the main difference between the three states of matter?

    <p>All of the above</p> Signup and view all the answers

    What is the characteristic of particles in a liquid state?

    <p>They are widely spaced and have random motion</p> Signup and view all the answers

    What is the result of an increase in kinetic energy of particles of matter?

    <p>They move faster and spread out</p> Signup and view all the answers

    What is the characteristic of particles of matter that determines their physical behavior?

    <p>All of the above</p> Signup and view all the answers

    What is the main postulate of the kinetic theory of matter?

    <p>Matter is made up of atoms, molecules, or ions in constant motion</p> Signup and view all the answers

    What is the result of particles being in a state of random continuous motion?

    <p>They diffuse and spread out</p> Signup and view all the answers

    What is the characteristic of particles in a gas state?

    <p>They are widely spaced and have random motion</p> Signup and view all the answers

    What is a characteristic of particles in a liquid state?

    <p>They are loosely packed and their positions are not fixed</p> Signup and view all the answers

    What is the primary difference between a liquid and a gas?

    <p>Liquids have a definite volume, while gases do not</p> Signup and view all the answers

    What is the reason why liquids cannot be compressed?

    <p>Their particles are loosely packed and have freedom of motion</p> Signup and view all the answers

    What is the characteristic of particles in a gas state?

    <p>They are wide apart and their positions are not fixed</p> Signup and view all the answers

    What is the primary difference between the density of a liquid and a gas?

    <p>Liquids have a higher density, while gases have a lower density</p> Signup and view all the answers

    What is the characteristic of particles in a liquid state that allows them to flow?

    <p>They are loosely packed and their positions are not fixed</p> Signup and view all the answers

    What is the characteristic of particles in a liquid state?

    <p>Particles are loosely packed and their positions are not fixed</p> Signup and view all the answers

    What is the main difference between the energy associated with particles in a liquid and a gas?

    <p>Particles in a liquid have considerable energy, while in a gas they have maximum energy</p> Signup and view all the answers

    What is the characteristic of a liquid in terms of its shape and volume?

    <p>A liquid has a definite volume but no definite shape</p> Signup and view all the answers

    What is the characteristic of particles in a gas?

    <p>Particles are wide apart and their positions are not fixed</p> Signup and view all the answers

    What is the characteristic of a gas in terms of its compressibility?

    <p>A gas can be compressed and is not rigid</p> Signup and view all the answers

    What is the characteristic of a liquid in terms of its density?

    <p>A liquid has a relatively high density</p> Signup and view all the answers

    What is the reason why a wooden block is considered a solid?

    <p>It has a fixed shape and is rigid</p> Signup and view all the answers

    Why is a rubber band considered a solid?

    <p>It regains its shape when the force is removed</p> Signup and view all the answers

    What is a characteristic of molecules in a solid?

    <p>They have a strong force of attraction between them</p> Signup and view all the answers

    What is a characteristic of molecules in a liquid?

    <p>They lie far apart from each other</p> Signup and view all the answers

    What happens to the shape of a rubber band when a force is applied?

    <p>It undergoes a change in shape</p> Signup and view all the answers

    What is a characteristic of molecules in a solid state?

    <p>They have a fixed position</p> Signup and view all the answers

    What is the reason why a rubber band is considered a solid, despite undergoing a change in shape?

    <p>It regains its shape when the force is removed</p> Signup and view all the answers

    What is a characteristic of the kinetic model of a solid?

    <p>Molecules have a fixed position</p> Signup and view all the answers

    What is the primary reason why a rubber band is considered a solid?

    <p>It regains its original shape when the force is removed</p> Signup and view all the answers

    What is a characteristic of the molecules in a solid?

    <p>They are closely packed</p> Signup and view all the answers

    What is the main difference between the molecules in a solid and a liquid?

    <p>The molecules in a liquid are farther apart than those in a solid</p> Signup and view all the answers

    Why is a wooden block considered a solid?

    <p>It has a fixed shape and is rigid</p> Signup and view all the answers

    What is the characteristic of the molecules in a liquid that allows them to move freely?

    <p>The intermolecular force of attraction between the molecules is not strong enough to keep them bonded to one position</p> Signup and view all the answers

    What is the main characteristic of a solid?

    <p>It has a fixed shape and is rigid</p> Signup and view all the answers

    What is the arrangement of molecules in a solid?

    <p>They are arranged in a definite manner</p> Signup and view all the answers

    What is the primary reason why a solid maintains its shape?

    <p>The molecules are fixed in position</p> Signup and view all the answers

    What is the force that resists the relative motion of layers in a flowing liquid?

    <p>Frictional force</p> Signup and view all the answers

    Why does glycerine have a higher viscosity than water or alcohol?

    <p>Because of its stronger intermolecular forces</p> Signup and view all the answers

    What happens to the viscosity of a liquid when its temperature increases?

    <p>It decreases</p> Signup and view all the answers

    What is the term for the internal friction or resistance in a flowing liquid?

    <p>Viscosity</p> Signup and view all the answers

    Which of the following liquids is more viscous?

    <p>Honey</p> Signup and view all the answers

    What is the result of the relative motion between layers in a flowing liquid?

    <p>Increased friction</p> Signup and view all the answers

    What is the force responsible for the stationary layer of liquid near a plate?

    <p>Friction</p> Signup and view all the answers

    What is the relationship between intermolecular forces and viscosity?

    <p>Stronger intermolecular forces lead to higher viscosity</p> Signup and view all the answers

    What is the effect of increasing temperature on the intermolecular forces in a liquid?

    <p>It decreases the intermolecular forces</p> Signup and view all the answers

    What is the term for the resistance to flow in a liquid caused by molecular forces?

    <p>Viscosity</p> Signup and view all the answers

    What is the reason for the surface tension of a liquid?

    <p>The intermolecular forces between surface molecules are unbalanced</p> Signup and view all the answers

    What happens to the surface tension of a liquid when the temperature is increased?

    <p>It decreases</p> Signup and view all the answers

    What is the relationship between surface tension and intermolecular attractive forces?

    <p>Surface tension is directly proportional to intermolecular forces</p> Signup and view all the answers

    What is the characteristic of the layer of liquid in contact with the wall of a tube?

    <p>It is stationary</p> Signup and view all the answers

    What is the term for the property of a liquid that resists flow?

    <p>Viscosity</p> Signup and view all the answers

    What is the velocity profile of a liquid flowing through a tube?

    <p>Highest in the centre and lowest at the wall</p> Signup and view all the answers

    What is the effect of temperature on intermolecular forces in a liquid?

    <p>It decreases them</p> Signup and view all the answers

    What is the reason for the difference in velocity between the centre and the wall of a tube?

    <p>Friction between the liquid and the wall</p> Signup and view all the answers

    What is the characteristic of a liquid with high surface tension?

    <p>It has strong intermolecular forces</p> Signup and view all the answers

    What is the effect of surface tension on the Cleaning ability of a liquid?

    <p>It increases the cleaning ability</p> Signup and view all the answers

    What is the reason for the surface tension of a liquid?

    <p>Because of the attractive forces between molecules</p> Signup and view all the answers

    What happens to the surface tension of a liquid when the temperature increases?

    <p>It decreases</p> Signup and view all the answers

    What is the property of a liquid that is responsible for its ability to flow through a tube?

    <p>Viscosity</p> Signup and view all the answers

    Why do the molecules at the surface of a liquid experience an unbalanced force?

    <p>Because of the attractive forces from molecules below</p> Signup and view all the answers

    What is the result of the unbalanced force at the surface of a liquid?

    <p>The surface molecules experience a net downward force</p> Signup and view all the answers

    What is the effect of temperature on the intermolecular forces between molecules of a liquid?

    <p>Intermolecular forces decrease with temperature</p> Signup and view all the answers

    What is the relationship between the magnitude of surface tension and intermolecular attractive forces?

    <p>The magnitude of surface tension is directly proportional to the intermolecular attractive forces</p> Signup and view all the answers

    What is the property of a liquid that determines its ability to resist changes in shape?

    <p>Surface tension</p> Signup and view all the answers

    What is the direction of motion of the layer of liquid in contact with the wall of a tube?

    <p>Stationary</p> Signup and view all the answers

    What is the velocity of the liquid in the centre of a tube?

    <p>Highest</p> Signup and view all the answers

    What is the internal friction or resistance that resists the relative motion of a liquid?

    <p>Viscosity</p> Signup and view all the answers

    Why does glycerine have more viscosity than water or alcohol?

    <p>Due to stronger intermolecular forces</p> Signup and view all the answers

    What happens to the viscosity of a liquid when the temperature is increased?

    <p>It decreases</p> Signup and view all the answers

    What is the reason for the stationary layer in contact with the glass plate in a liquid flowing over it?

    <p>Due to adhesion</p> Signup and view all the answers

    What is the characteristics of a liquid with high viscosity?

    <p>It flows with difficulty</p> Signup and view all the answers

    What is the relation between intermolecular forces and viscosity?

    <p>Strong intermolecular forces lead to high viscosity</p> Signup and view all the answers

    What is the result of the relative motion between different layers of a liquid?

    <p>Each layer exerts a drag on the next</p> Signup and view all the answers

    What is the reason for the continuous increase in velocity of different layers of a liquid flowing over a glass plate?

    <p>Due to relative motion</p> Signup and view all the answers

    What is the characteristic of honey that makes it more viscous than water?

    <p>Stronger intermolecular forces</p> Signup and view all the answers

    What is the result of the work done to maintain the flow of a liquid?

    <p>It maintains the flow of the liquid</p> Signup and view all the answers

    What is the primary reason for the surface tension of a liquid?

    <p>Intermolecular attractive forces</p> Signup and view all the answers

    What happens to the surface tension of a liquid when its temperature is increased?

    <p>It decreases</p> Signup and view all the answers

    What is the relationship between surface tension and the nature of a liquid?

    <p>Surface tension is a measure of intermolecular attractive forces</p> Signup and view all the answers

    What is the characteristic of liquid flow through a tube?

    <p>The layer in contact with the tube is stationary</p> Signup and view all the answers

    What is the property of a liquid that causes it to resist changes in shape?

    <p>Viscosity</p> Signup and view all the answers

    What is the effect of increasing temperature on the viscosity of a liquid?

    <p>It decreases the viscosity</p> Signup and view all the answers

    What is the relationship between the velocity of liquid layers in a tube?

    <p>The velocity of the layers decreases from the center to the wall</p> Signup and view all the answers

    What is the force responsible for the surface tension of a liquid?

    <p>Intermolecular attractive force</p> Signup and view all the answers

    What is the result of the imbalance of forces at the surface of a liquid?

    <p>The liquid surface is under tension</p> Signup and view all the answers

    Why do clothes get washed more efficiently in hot water?

    <p>Because of decreased surface tension</p> Signup and view all the answers

    What is the reason for the internal resistance or viscosity in a liquid?

    <p>Molecular force working between the molecules of the liquid</p> Signup and view all the answers

    What happens to the velocity of different layers of a liquid flowing over a glass plate?

    <p>The velocity of different layers increases continuously with the distance from the fixed surface</p> Signup and view all the answers

    Why does glycerine have more viscosity than water or alcohol?

    <p>Glycerine has a higher intermolecular force</p> Signup and view all the answers

    What is the effect of temperature on the viscosity of a liquid?

    <p>Viscosity decreases with an increase in temperature</p> Signup and view all the answers

    What is the reason for the difference in viscosity between honey and water?

    <p>Honey has a stronger intermolecular force</p> Signup and view all the answers

    What is the role of each layer in a liquid flowing through a pipe?

    <p>Each layer exerts a drag on the next layer</p> Signup and view all the answers

    What is the characteristic of a liquid with high viscosity?

    <p>It flows slowly and with difficulty</p> Signup and view all the answers

    What is the relationship between intermolecular forces and viscosity?

    <p>High intermolecular forces result in high viscosity</p> Signup and view all the answers

    What is the reason for the difference in flow of glycerine and water?

    <p>Glycerine has a higher intermolecular force</p> Signup and view all the answers

    What is the characteristic of a liquid with low viscosity?

    <p>It flows easily and quickly</p> Signup and view all the answers

    What is the state of matter of bromine at a temperature greater than -7.2°C but less than 59°C?

    <p>Liquid</p> Signup and view all the answers

    What is the primary reason why gases exert pressure?

    <p>Due to constant collision and bombardment on the walls of the vessel</p> Signup and view all the answers

    What is true about the composition of gases?

    <p>They have similar composition in all parts</p> Signup and view all the answers

    What is the result of applying pressure and cooling to a gas?

    <p>It becomes a liquid</p> Signup and view all the answers

    What is the reason why gases fill the entire space of their container?

    <p>Due to high kinetic energy and low intermolecular forces</p> Signup and view all the answers

    What is the direction of pressure exerted by a gas?

    <p>In all directions</p> Signup and view all the answers

    What is the term for the movement of particles in a gas?

    <p>Diffusion</p> Signup and view all the answers

    What is true about the molecules of a gas?

    <p>They have high kinetic energy and large intermolecular spaces</p> Signup and view all the answers

    What happens when the kinetic energy of particles of matter increases?

    <p>They move randomly</p> Signup and view all the answers

    What is the term for the theory that describes matter as consisting of atoms, molecules, or ions in constant motion?

    <p>Kinetic theory of matter</p> Signup and view all the answers

    What is the term for the force that exists between particles of matter in a liquid state?

    <p>Intermolecular forces</p> Signup and view all the answers

    What is the state of matter of bromine at a temperature greater than -7.2°C but less than 59°C?

    <p>Liquid</p> Signup and view all the answers

    What is the main reason why gases exert pressure in all directions?

    <p>Due to the constant collision of molecules with the container walls</p> Signup and view all the answers

    What is the characteristic of gases that allows them to fill completely the vessel they are contained in?

    <p>Large intermolecular spaces and high kinetic energy</p> Signup and view all the answers

    What is the process by which gases can be converted into liquids?

    <p>Liquefaction</p> Signup and view all the answers

    What is the characteristic of gases that makes them homogeneous in nature?

    <p>Similar composition in all parts</p> Signup and view all the answers

    What is the result of the constant collision of gas molecules with the container walls?

    <p>The gas exerts pressure on the container walls</p> Signup and view all the answers

    What is the primary difference between the movement of gas molecules and liquid molecules?

    <p>Gas molecules move faster than liquid molecules</p> Signup and view all the answers

    What is the characteristic of a liquid that allows it to take the shape of its container?

    <p>Definite volume and no definite shape</p> Signup and view all the answers

    What is the result of the high kinetic energy of gas molecules?

    <p>The gas molecules spread out and fill the container</p> Signup and view all the answers

    What is the characteristic of gases that allows them to exert pressure in all directions?

    <p>Negligible force of attraction between molecules</p> Signup and view all the answers

    What is the term for the process by which gases intermix with one another without any mechanical aid?

    <p>Diffusion</p> Signup and view all the answers

    What is the main application of Graham's law of diffusion?

    <p>All of the above</p> Signup and view all the answers

    What are the three states of matter that are interconvertible?

    <p>Solid, liquid, and gas</p> Signup and view all the answers

    What is the change in condition necessary for the interconversion of states of matter?

    <p>All of the above</p> Signup and view all the answers

    What happens when a bottle of ammonia is opened in a laboratory?

    <p>Its pungent smell can be experienced all over the laboratory</p> Signup and view all the answers

    What is the result of heating ice above 0°C?

    <p>It changes into a liquid state</p> Signup and view all the answers

    What happens when a candle is lit up?

    <p>The wax melts and rises up the wick</p> Signup and view all the answers

    What is the process by which gases are separated from a mixture?

    <p>Diffusion</p> Signup and view all the answers

    What is the result of further heating a liquid above 100°C?

    <p>It changes into a gaseous state</p> Signup and view all the answers

    What is the characteristic of gases that allows them to intermix with one another?

    <p>They are able to form a homogeneous mixture</p> Signup and view all the answers

    What is the process of converting gases into liquid state?

    <p>By increasing the pressure of the gas</p> Signup and view all the answers

    Why does the temperature of the system not change after the melting point is achieved?

    <p>Because the heat is used to change the state of the substance</p> Signup and view all the answers

    What is the term for the energy required to change a solid into a liquid?

    <p>Latent heat</p> Signup and view all the answers

    What happens when a substance changes its state?

    <p>It can be reverted to its original state by altering its temperature or pressure</p> Signup and view all the answers

    Why can sugar not be converted from solid to liquid?

    <p>Because it decomposes when heated</p> Signup and view all the answers

    What happens when the temperature of a substance is changed?

    <p>Its physical state changes</p> Signup and view all the answers

    What is the term for the change of state of a substance?

    <p>Phase transition</p> Signup and view all the answers

    Why is latent heat called 'hidden heat'?

    <p>Because it is hidden in the system</p> Signup and view all the answers

    What is the result of increasing the pressure of a gas?

    <p>The gas becomes a liquid</p> Signup and view all the answers

    What is the relationship between the temperature and physical state of a substance?

    <p>Temperature determines the physical state</p> Signup and view all the answers

    What is the property that allows ammonia to spread its smell all over the laboratory?

    <p>Diffusion</p> Signup and view all the answers

    According to Graham's law of diffusion, what can be determined?

    <p>Relative densities and molecular weights of gases</p> Signup and view all the answers

    What is the process of changing a mixture of gases into individual gases?

    <p>Separation</p> Signup and view all the answers

    What are the three main states of matter?

    <p>Solid, Liquid, Gas</p> Signup and view all the answers

    What is the term for the process of changing from one state of matter to another?

    <p>Interconversion</p> Signup and view all the answers

    What is the result of heating ice?

    <p>It changes into a liquid state</p> Signup and view all the answers

    What is the result of heating water above 100°C?

    <p>It changes into a gas state</p> Signup and view all the answers

    What happens when a candle is lit?

    <p>The wax changes into a liquid state</p> Signup and view all the answers

    What is the process by which particles intermix and spread out?

    <p>Diffusion</p> Signup and view all the answers

    What is the result of decreasing the pressure of a gas?

    <p>It remains in a gas state</p> Signup and view all the answers

    What is necessary to convert gases such as nitrogen, oxygen, hydrogen, and helium into a liquid state?

    <p>Cooling and increasing the pressure of the gas</p> Signup and view all the answers

    Why does the temperature of a system not change after the melting point is achieved until all the ice melts?

    <p>The heat supplied is used to change the state by breaking the intermolecular forces of attraction</p> Signup and view all the answers

    What is the energy required to change a solid into a liquid called?

    <p>Latent heat</p> Signup and view all the answers

    What happens when a substance changes its state?

    <p>It can be reverted to the original state by altering its temperature or pressure</p> Signup and view all the answers

    Why can't sugar be changed from a solid to a liquid state?

    <p>Because sugar decomposes when heated</p> Signup and view all the answers

    What is the term for the temperature at which a substance changes from a solid to a liquid state?

    <p>Melting point</p> Signup and view all the answers

    What happens when a substance is heated and changes its physical state?

    <p>Its physical properties change</p> Signup and view all the answers

    What is the result of changing the pressure of a gas?

    <p>The gas changes its physical state</p> Signup and view all the answers

    Why is it not essential that all substances can be changed from one state to another?

    <p>Because some substances decompose when heated</p> Signup and view all the answers

    What is the term used to describe the energy required to change a solid into a liquid?

    <p>Latent heat of fusion</p> Signup and view all the answers

    What is the term used to describe the process of gases intermixing with one another without any mechanical aid?

    <p>Diffusion</p> Signup and view all the answers

    What is the purpose of Graham's law of diffusion?

    <p>To determine the relative densities and molecular weights of gases</p> Signup and view all the answers

    What happens to the smell of ammonia when a bottle is opened in one corner of a laboratory?

    <p>It can be experienced all over the laboratory</p> Signup and view all the answers

    What is the result of heating ice, which is water in a solid state?

    <p>It changes into a liquid state</p> Signup and view all the answers

    What are the three forms of matter that are interconvertible?

    <p>Solid, liquid, and gas</p> Signup and view all the answers

    What is the result of further heating the water after it changes into a liquid state?

    <p>It changes into a gas state</p> Signup and view all the answers

    What happens to the wax in a candle when it is lit up?

    <p>It changes into a liquid state</p> Signup and view all the answers

    What is the purpose of diffusion in separating gases from a mixture?

    <p>To separate gases based on their molecular weights</p> Signup and view all the answers

    What is the term used to describe the process of gases spreading and intermixing with one another?

    <p>Diffusion</p> Signup and view all the answers

    What is the result of repeating the process of diffusion to separate gases from a mixture?

    <p>Gases can be completely separated</p> Signup and view all the answers

    What is the process of converting gases like nitrogen, oxygen, hydrogen, and helium into a liquid state?

    <p>Cooling and increasing pressure</p> Signup and view all the answers

    Why does sugar not change into liquid sugar when heated?

    <p>Because the sugar changes into a decomposed substance after heating</p> Signup and view all the answers

    What is the energy required to change a solid into a liquid called?

    <p>Latent heat</p> Signup and view all the answers

    What happens to the temperature of a system when it reaches the melting point?

    <p>It remains constant until all the ice melts</p> Signup and view all the answers

    What is the term for the heat supplied to change the state of a substance?

    <p>Latent heat</p> Signup and view all the answers

    Why does the heat supplied to a system not change the temperature until all the ice melts?

    <p>Because the heat is used to change the state of the system</p> Signup and view all the answers

    What is the result of altering the temperature of a substance?

    <p>It changes its state</p> Signup and view all the answers

    What can cause a gas to change its state?

    <p>Changing the pressure</p> Signup and view all the answers

    What is the energy required to change a solid into a liquid also known as?

    <p>Latent heat</p> Signup and view all the answers

    What is the purpose of latent heat in a system?

    <p>To change the state of the system</p> Signup and view all the answers

    What is the amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure without any change in temperature?

    <p>Latent heat of fusion</p> Signup and view all the answers

    What happens to the molecules of a solid when it is subjected to heating?

    <p>Their kinetic energy increases</p> Signup and view all the answers

    What is the term for the temperature at which a solid gets converted to a liquid state at atmospheric pressure?

    <p>Melting point</p> Signup and view all the answers

    What is the effect of pressure on the melting point of solids that expand on melting?

    <p>It increases the melting point</p> Signup and view all the answers

    What is the latent heat of fusion of ice?

    <p>3.34 x 10^5 J/kg</p> Signup and view all the answers

    What is the state of water at 100°C?

    <p>Vapour</p> Signup and view all the answers

    What is the effect of pressure on the melting point of solids that contract on melting?

    <p>It decreases the melting point</p> Signup and view all the answers

    What is the change in the molecular arrangement of a solid during melting?

    <p>It changes from solid to liquid</p> Signup and view all the answers

    What is the type of heat energy required to change 1 kg of a liquid into a vapour at atmospheric pressure without any change in temperature?

    <p>Latent heat of vaporization</p> Signup and view all the answers

    What is the graph of temperature against time for the change from ice at -15°C to water and further to steam?

    <p>A curved line</p> Signup and view all the answers

    What is latent heat of fusion?

    <p>The amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure</p> Signup and view all the answers

    What is the latent heat of fusion of ice?

    <p>3.34 x 10^5 J/kg</p> Signup and view all the answers

    What happens to the molecules when a solid is heated?

    <p>They absorb heat energy and increase their kinetic energy</p> Signup and view all the answers

    What is the temperature at which a solid changes to a liquid state at atmospheric pressure?

    <p>Melting point</p> Signup and view all the answers

    What happens to the melting point of a solid that expands on melting when the pressure is increased?

    <p>It increases</p> Signup and view all the answers

    What is the effect of pressure on the melting point of paraffin wax?

    <p>It increases the melting point</p> Signup and view all the answers

    What is the process by which the molecular arrangement of a solid changes to that of a liquid?

    <p>Melting</p> Signup and view all the answers

    What is the graph of temperature against time for the change from ice to water and further to steam?

    <p>A step-wise line</p> Signup and view all the answers

    What is the melting point of ice?

    <p>0°C</p> Signup and view all the answers

    What is the effect of pressure on the melting point of cast iron?

    <p>It decreases the melting point</p> Signup and view all the answers

    What is the main effect of adding impurities to a solid?

    <p>Decrease the melting point of the solid</p> Signup and view all the answers

    What is the melting point of Rose's metal?

    <p>94.5°C</p> Signup and view all the answers

    What is the process of conversion of a liquid state to a solid state called?

    <p>Freezing</p> Signup and view all the answers

    What is the unique property of ice that makes it less dense than water?

    <p>Its molecules form a latticework of hexagons</p> Signup and view all the answers

    Why do fish and aquatic animals survive in frozen lakes?

    <p>Because ice is less dense than water</p> Signup and view all the answers

    What is the freezing point of a liquid?

    <p>The temperature at which a liquid converts into a solid at atmospheric pressure</p> Signup and view all the answers

    What is the main reason why ice floats on water?

    <p>Because ice is less dense than water</p> Signup and view all the answers

    What is the density of ice?

    <p>0.917 g/cm3</p> Signup and view all the answers

    What is the main problem caused by the expansion of ice on land?

    <p>All of the above</p> Signup and view all the answers

    What is the percentage of ice that remains below the water's surface?

    <p>90%</p> Signup and view all the answers

    What is the effect of adding impurities to a solid?

    <p>Decrease the melting point of the solid</p> Signup and view all the answers

    What is the melting point of Rose's metal?

    <p>94.5°C</p> Signup and view all the answers

    What is the freezing point of a liquid?

    <p>The temperature at which a liquid converts into a solid</p> Signup and view all the answers

    Why does ice float on water?

    <p>Because it is less dense than water</p> Signup and view all the answers

    What is the density of ice?

    <p>0.917 g/cm³</p> Signup and view all the answers

    Why can fish survive in frozen lakes?

    <p>Because ice is less dense than water</p> Signup and view all the answers

    What happens to the volume of water when it freezes?

    <p>It increases by 77%</p> Signup and view all the answers

    What is the main reason for the weathering of paved surfaces?

    <p>The expansion of ice</p> Signup and view all the answers

    What is the purpose of freezing mixtures?

    <p>To preserve food</p> Signup and view all the answers

    What is the composition of a freezing mixture used to produce a lower temperature?

    <p>3 parts of ice and 1 part of common salt</p> Signup and view all the answers

    What is the process by which a liquid changes into a gaseous state by absorbing heat energy called?

    <p>Boiling</p> Signup and view all the answers

    What is the quantity of heat in joules required to convert 1 kilogram of a liquid to vapour or gas, without any change in temperature?

    <p>Latent heat of vaporization</p> Signup and view all the answers

    What is the conversion formula from Celsius to Kelvin scale?

    <p>K = °C + 273</p> Signup and view all the answers

    What is the boiling point of a liquid defined as?

    <p>The constant temperature at which a liquid rapidly changes into a gaseous state by absorbing heat energy at atmospheric pressure</p> Signup and view all the answers

    What is the latent heat of vaporization of water?

    <p>22.5 x 10^5 J/kg</p> Signup and view all the answers

    What is the conversion formula from Fahrenheit to Celsius scale?

    <p>°C = (°F - 32) x 5/9</p> Signup and view all the answers

    What is the temperature at which vapour pressure of a liquid becomes equal to atmospheric pressure?

    <p>Boiling point</p> Signup and view all the answers

    What is the process by which a liquid changes into a solid state by releasing heat energy called?

    <p>Freezing</p> Signup and view all the answers

    What is the conversion formula from Kelvin to Celsius scale?

    <p>°C = K - 273</p> Signup and view all the answers

    What is the unit of latent heat of vaporization?

    <p>J/kg</p> Signup and view all the answers

    What is the process called when a liquid changes into a gaseous state by absorbing heat energy?

    <p>Boiling</p> Signup and view all the answers

    What is the latent heat of vaporization of water?

    <p>22.5 x 10^3 J/kg</p> Signup and view all the answers

    What is the temperature in Celsius when the temperature in Kelvin is 573 K?

    <p>300°C</p> Signup and view all the answers

    What is the formula to convert Fahrenheit to Celsius?

    <p>(F - 32) * 5/9</p> Signup and view all the answers

    What is the boiling point of a liquid?

    <p>The constant temperature at which the liquid rapidly changes into a gaseous state</p> Signup and view all the answers

    What is the relationship between the vapour pressure of a liquid and the atmospheric pressure at the boiling point?

    <p>The vapour pressure is equal to the atmospheric pressure</p> Signup and view all the answers

    What is the result of converting 108°F to Celsius?

    <p>42.2°C</p> Signup and view all the answers

    What is the temperature in Kelvin when the temperature in Celsius is 27°C?

    <p>300 K</p> Signup and view all the answers

    What is the latent heat of vaporization of a liquid?

    <p>The quantity of heat required to change the state of a liquid to a gas</p> Signup and view all the answers

    What is the correct conversion of 300 K to Celsius?

    <p>27°C</p> Signup and view all the answers

    What is the process by which water vapour in the air condenses into dew or frost?

    <p>Condensation</p> Signup and view all the answers

    What happens when the air becomes saturated with water vapour?

    <p>Condensation occurs</p> Signup and view all the answers

    What is the term for the temperature at which the air becomes saturated with water vapour?

    <p>Dew point</p> Signup and view all the answers

    What is the phenomenon by which a substance changes directly from solid to gas without going through the liquid phase?

    <p>Sublimation</p> Signup and view all the answers

    What type of particles can condensation occur on to form fog or mist?

    <p>Dust particles</p> Signup and view all the answers

    What is the term for the formation of water droplets in the upper part of the atmosphere?

    <p>Clouds</p> Signup and view all the answers

    What is an example of a substance that exhibits sublimation?

    <p>All of the above</p> Signup and view all the answers

    What is the result of the condensation of water vapour on floating dust particles?

    <p>Fog or mist</p> Signup and view all the answers

    What is the opposite process of condensation?

    <p>Evaporation</p> Signup and view all the answers

    What is the term for the process by which a liquid changes directly into a gas or vapour?

    <p>Evaporation</p> Signup and view all the answers

    What happens to the boiling point of a liquid when the external pressure is increased?

    <p>It increases</p> Signup and view all the answers

    Why does food cook faster in a pressure cooker?

    <p>Due to the increase in steam generated</p> Signup and view all the answers

    What is the effect of adding impurities to a liquid on its boiling point?

    <p>It increases the boiling point</p> Signup and view all the answers

    Why does it take longer to cook food in the hills?

    <p>Due to the lower atmospheric pressure</p> Signup and view all the answers

    What is the process of changing a gas or vapour into a liquid by cooling?

    <p>Condensation</p> Signup and view all the answers

    What happens to the kinetic energy of particles when a gas or vapour is cooled?

    <p>It decreases</p> Signup and view all the answers

    What is the result of the attractive forces between particles when a gas or vapour is cooled?

    <p>The particles attract each other and condense</p> Signup and view all the answers

    Why does water boil at a lower temperature at higher altitudes?

    <p>Due to the lower atmospheric pressure</p> Signup and view all the answers

    What is the effect of pressure on the boiling point of a liquid?

    <p>It increases the boiling point</p> Signup and view all the answers

    What is the effect of increasing external pressure on the boiling point of a liquid?

    <p>It increases</p> Signup and view all the answers

    What happens to the boiling point of a liquid when a solid substance is dissolved in it?

    <p>It increases</p> Signup and view all the answers

    Why does it take longer to cook food in the hills than in the plains?

    <p>Because of low air pressure</p> Signup and view all the answers

    What is the process of changing a gas or vapour to a liquid by cooling?

    <p>Condensation</p> Signup and view all the answers

    At what temperature does water boil at sea level?

    <p>373 K</p> Signup and view all the answers

    What is the effect of external pressure on the boiling point of a liquid?

    <p>It increases the boiling point</p> Signup and view all the answers

    What is the result of condensation of water vapor on floating dust particles?

    <p>Fog or mist formation</p> Signup and view all the answers

    Why does food cook faster in a pressure cooker?

    <p>Because of high pressure</p> Signup and view all the answers

    What happens to the kinetic energy of particles when a gas or vapour is cooled?

    <p>It decreases</p> Signup and view all the answers

    What is the term used to describe the temperature at which the air becomes saturated with water vapor?

    <p>Dew point</p> Signup and view all the answers

    What is the process by which a substance changes directly from the solid to the gaseous state?

    <p>Sublimation</p> Signup and view all the answers

    What is the result of the attractive forces between particles in a gas or vapour when it is cooled?

    <p>The particles come close together</p> Signup and view all the answers

    What is an example of a substance that exhibits sublimation?

    <p>All of the above</p> Signup and view all the answers

    What is the result of condensation of water vapor in the upper part of the atmosphere?

    <p>Cloud formation</p> Signup and view all the answers

    What is the process by which water in water bodies evaporates during the day?

    <p>Evaporation</p> Signup and view all the answers

    What happens to the air when the temperature falls during nighttime?

    <p>It becomes saturated with water vapor</p> Signup and view all the answers

    What is the result of further cooling of the air after it becomes saturated with water vapor?

    <p>Dew formation</p> Signup and view all the answers

    What is the process by which water droplets condense as dew?

    <p>Condensation</p> Signup and view all the answers

    What is an example of a situation where condensation occurs?

    <p>All of the above</p> Signup and view all the answers

    What is the effect of increasing external pressure on the boiling point of a liquid?

    <p>It increases the boiling point</p> Signup and view all the answers

    Why does food cook faster in a pressure cooker?

    <p>Because the steam generated increases the pressure</p> Signup and view all the answers

    What happens when a solid substance is dissolved in a liquid?

    <p>The boiling point of the liquid increases</p> Signup and view all the answers

    What is the process by which water vapor changes directly into a solid state?

    <p>Sublimation</p> Signup and view all the answers

    What is the term for the temperature at which the air becomes saturated with water vapor?

    <p>Dew point</p> Signup and view all the answers

    Why does it take longer to cook food in the hills than in the plains?

    <p>Because the boiling point of the liquid is lower in the hills</p> Signup and view all the answers

    What is the process of changing a gas or vapour to a liquid by cooling?

    <p>Condensation</p> Signup and view all the answers

    What is the result of the condensation of water vapor on floating dust particles?

    <p>Fog or mist formation</p> Signup and view all the answers

    What is the state of matter that is characterized by random continuous motion?

    <p>Gas</p> Signup and view all the answers

    What happens when the kinetic energy of particles decreases?

    <p>The particles move slower</p> Signup and view all the answers

    What is the effect of increasing the pressure on the boiling point of a liquid at sea level?

    <p>The boiling point increases</p> Signup and view all the answers

    What is the process by which water in water bodies changes into water vapor?

    <p>Evaporation</p> Signup and view all the answers

    Why does water boil at a lower temperature in the hills than at sea level?

    <p>Because the pressure is less in the hills</p> Signup and view all the answers

    What is the result of the condensation of water vapor in the upper part of the atmosphere?

    <p>Cloud formation</p> Signup and view all the answers

    What is the reason why a pressure cooker can cook food faster than a normal vessel?

    <p>Because the steam generated increases the pressure</p> Signup and view all the answers

    What is an example of a substance that exhibits sublimation?

    <p>Ammonium chloride</p> Signup and view all the answers

    What is the state of matter that is characterized by particles that are closely packed and have a fixed shape?

    <p>Solid</p> Signup and view all the answers

    What is the process by which water vapor changes into a liquid state?

    <p>Condensation</p> Signup and view all the answers

    What is the result of the condensation of water vapor on a surface?

    <p>Dew formation</p> Signup and view all the answers

    What happens when carbon dioxide is cooled under high pressure?

    <p>It turns directly into dry ice.</p> Signup and view all the answers

    Why does dry ice not wet the surface it is kept on?

    <p>Because it sublimes.</p> Signup and view all the answers

    What is the name under which dry ice is used as a refrigerant?

    <p>Dricold</p> Signup and view all the answers

    What is the process by which iodine changes directly from a solid to a gas?

    <p>Sublimation</p> Signup and view all the answers

    What is deposited on the upper part of a test tube when iodine sublimes?

    <p>A grey powder</p> Signup and view all the answers

    What is the term for a substance that can exist in a gaseous state under specific conditions?

    <p>Vapour</p> Signup and view all the answers

    What happens to the spaces between gaseous particles when pressure is applied?

    <p>They decrease in size.</p> Signup and view all the answers

    What happens to a liquefied gas if the pressure is further increased and the temperature is further lowered?

    <p>It turns into a solid.</p> Signup and view all the answers

    What is the term for the process of a liquid changing into a vapour state even below its boiling point?

    <p>Evaporation</p> Signup and view all the answers

    Under ordinary circumstances, what state of matter will a substance remain as at room temperature and one atmospheric pressure?

    <p>Gas</p> Signup and view all the answers

    What is the reason why surface molecules of a liquid possess higher kinetic energies than the molecules in the bulk?

    <p>Due to the random motion of the molecules</p> Signup and view all the answers

    What happens when the molecules of a liquid break away from the forces of attraction of the other molecules?

    <p>They go into vapour state</p> Signup and view all the answers

    What is the state of matter that iodine turns into when heated?

    <p>Vapour</p> Signup and view all the answers

    What is the energy associated with the motion of molecules?

    <p>Kinetic energy</p> Signup and view all the answers

    What is the process by which a liquid changes into a vapour state?

    <p>Vaporization</p> Signup and view all the answers

    What is the state of matter that oxygen remains as at room temperature and one atmospheric pressure?

    <p>Gas</p> Signup and view all the answers

    What is the reason why a substance remains as a gas at room temperature and one atmospheric pressure?

    <p>Due to its ordinary circumstances</p> Signup and view all the answers

    What happens to solid iodine when it is heated?

    <p>It turns into a vapour</p> Signup and view all the answers

    What is the process of a liquid changing into a vapour state below its boiling point called?

    <p>Evaporation</p> Signup and view all the answers

    What is the reason why surface molecules in a liquid can break away and turn into vapour?

    <p>They have higher kinetic energies</p> Signup and view all the answers

    What remains the same for a substance that exists as a gas under ordinary circumstances?

    <p>Its chemical composition</p> Signup and view all the answers

    What is the state of a substance that can change into a vapour state even without heat energy?

    <p>Liquid</p> Signup and view all the answers

    What is the force that holds molecules together in a liquid?

    <p>Forces of attraction</p> Signup and view all the answers

    What is the reason why solid carbon dioxide is called dry ice?

    <p>It directly gets converted into the gaseous state without passing through the intervening liquid state</p> Signup and view all the answers

    What is the characteristic of iodine that makes it a sublimable substance?

    <p>It changes directly into a gaseous state without first melting</p> Signup and view all the answers

    What happens to the kinetic energy of particles in a substance when it is heated?

    <p>It increases</p> Signup and view all the answers

    What is the term for the process of a liquid changing into a gas at its boiling point?

    <p>Vaporization</p> Signup and view all the answers

    What is the effect of applying pressure on gases?

    <p>The spaces between the gaseous particles decrease</p> Signup and view all the answers

    What happens when a liquefied gas is subjected to further increased pressure and lowered temperature?

    <p>It changes into a solid state</p> Signup and view all the answers

    Why do surface molecules in a liquid have higher kinetic energies?

    <p>Because of their random motion</p> Signup and view all the answers

    What is the term for a substance that exists in a gaseous state under specific conditions?

    <p>Vapour</p> Signup and view all the answers

    What is the characteristic of naphthalene balls that makes them useful for preserving clothes?

    <p>They change directly into a gaseous state without wetting the clothes</p> Signup and view all the answers

    What is the process by which iodine changes directly into a gaseous state when heated?

    <p>Sublimation</p> Signup and view all the answers

    What is the characteristic of dry ice that makes it different from ordinary ice?

    <p>It does not wet the surface on which it is kept</p> Signup and view all the answers

    What is the effect of increasing the temperature of a liquid on its rate of evaporation?

    <p>It increases the rate of evaporation</p> Signup and view all the answers

    Which factor slows down the rate of evaporation?

    <p>High humidity</p> Signup and view all the answers

    What is the result of the molecules of a liquid absorbing energy from the surroundings during evaporation?

    <p>The surroundings lose energy</p> Signup and view all the answers

    Why do different liquids have different rates of evaporation?

    <p>Due to their different interparticle attractive forces</p> Signup and view all the answers

    What happens to the molecules of a liquid when they move from an area of higher pressure to an area of lower pressure?

    <p>They are sucked into the surrounding area</p> Signup and view all the answers

    What is the result of evaporation on the temperature of the surroundings?

    <p>It decreases the temperature</p> Signup and view all the answers

    Why does acetone evaporate faster than water?

    <p>Due to its weaker interparticle attractive forces</p> Signup and view all the answers

    What is the effect of wind speed on the rate of evaporation?

    <p>It increases the rate of evaporation</p> Signup and view all the answers

    Why do clothes take longer to dry in rainy season?

    <p>Due to the higher humidity</p> Signup and view all the answers

    What is the effect of increasing the surface area of a liquid on its rate of evaporation?

    <p>It increases the rate of evaporation</p> Signup and view all the answers

    What happens to the rate of evaporation when the temperature of the liquid is increased?

    <p>It increases</p> Signup and view all the answers

    Why do wet clothes dry faster in summer than in winter?

    <p>Because of the high temperature in summer</p> Signup and view all the answers

    What happens to the rate of evaporation when the surface area of the liquid is increased?

    <p>It increases</p> Signup and view all the answers

    Why does humidity of air lower the rate of evaporation?

    <p>Because of the high humidity</p> Signup and view all the answers

    What happens to the rate of evaporation when the wind speed is increased?

    <p>It increases</p> Signup and view all the answers

    What is the effect of pressure on the rate of evaporation?

    <p>Decreased pressure increases the rate of evaporation</p> Signup and view all the answers

    Why do different liquids have different rates of evaporation?

    <p>Because of their different interparticle attractive forces</p> Signup and view all the answers

    What is the cooling effect produced due to evaporation?

    <p>The liquid molecules absorb energy from the surroundings</p> Signup and view all the answers

    What is an example of the cooling effect produced due to evaporation?

    <p>The cooling produced when alcohol is poured on the palm</p> Signup and view all the answers

    What is the principle behind the cooling effect produced due to evaporation?

    <p>The principle of energy absorption from the surroundings</p> Signup and view all the answers

    Which factor increases the rate of evaporation of a liquid?

    <p>Increase in surface area</p> Signup and view all the answers

    What happens to the molecules when the vapour pressure of the surrounding air increases to a specific level?

    <p>They evaporate slower</p> Signup and view all the answers

    Why do different liquids have different rates of evaporation?

    <p>Due to their interparticle attractive forces</p> Signup and view all the answers

    What is the result of evaporation on the surroundings?

    <p>The surroundings lose energy</p> Signup and view all the answers

    Why does acetone evaporate faster than water?

    <p>Because acetone has weaker interparticle attractive forces</p> Signup and view all the answers

    What is the principle behind the cooling effect produced when alcohol is poured on the palm?

    <p>Evaporation</p> Signup and view all the answers

    What is the result of decreasing the pressure around a liquid?

    <p>The rate of evaporation increases</p> Signup and view all the answers

    Why do clothes dry faster in summer than in winter?

    <p>Because of the higher temperature in summer</p> Signup and view all the answers

    What is the effect of wind speed on the rate of evaporation?

    <p>It increases the rate of evaporation</p> Signup and view all the answers

    Why do clothes not dry easily in rainy season?

    <p>Because of the higher humidity</p> Signup and view all the answers

    What determines the colour of plasma glow?

    <p>The nature of the gas</p> Signup and view all the answers

    What is a Bose-Einstein condensate?

    <p>A type of super-cold superfluid</p> Signup and view all the answers

    What happens during evaporation?

    <p>Only high energy particles leave the liquid surface</p> Signup and view all the answers

    What is a characteristic of plasma?

    <p>It has neither a definite volume nor a definite shape</p> Signup and view all the answers

    What is the temperature at which molecular motion stops?

    <p>Absolute zero (0 K)</p> Signup and view all the answers

    What happens to atoms when cooled to near absolute zero?

    <p>They clump together</p> Signup and view all the answers

    What is the result of evaporation on the temperature of the remaining liquid?

    <p>It decreases the temperature</p> Signup and view all the answers

    Who predicted the Bose-Einstein condensate?

    <p>Satyendra Bose and Albert Einstein</p> Signup and view all the answers

    What is plasma composed of?

    <p>Charged particles</p> Signup and view all the answers

    Which of the following is an example of plasma?

    <p>A flame</p> Signup and view all the answers

    What is the temperature at which the first Bose-Einstein condensate was produced?

    <p>170 nK</p> Signup and view all the answers

    Why is plasma electrically conductive?

    <p>Because it is composed of charged particles</p> Signup and view all the answers

    What is the opposite of a super-hot plasma?

    <p>A super-cold superfluid</p> Signup and view all the answers

    What happens when atoms form a Bose-Einstein condensate?

    <p>They form a single entity</p> Signup and view all the answers

    What is the correct statement about plasma state?

    <p>The particles of plasma state are in the form of ionized gases.</p> Signup and view all the answers

    What is the term used to describe plasma?

    <p>Ionized gas</p> Signup and view all the answers

    What is the result of cooling atoms to near absolute zero?

    <p>The atoms become super-unexcited</p> Signup and view all the answers

    Who first identified plasma as 'radiant matter'?

    <p>Sir William Crookes</p> Signup and view all the answers

    Who produced the first Bose-Einstein condensate in 1995?

    <p>Eric Cornell, Ketterle, and Carl Wieman</p> Signup and view all the answers

    What is the primary factor that determines the colour of a plasma glow?

    <p>Temperature and nature of the gas</p> Signup and view all the answers

    What is the main reason why evaporation causes cooling?

    <p>Low energy particles are left behind</p> Signup and view all the answers

    What is the state of matter formed by atoms cooled to a temperature near absolute zero?

    <p>Bose-Einstein condensate</p> Signup and view all the answers

    What is the correct definition of plasma?

    <p>A state of matter that is created by heating and ionizing a gas</p> Signup and view all the answers

    What happens to molecular motion at a temperature of zero Kelvin?

    <p>It stops</p> Signup and view all the answers

    What is the result of atoms clumping together at super low temperatures?

    <p>A Bose-Einstein condensate forms</p> Signup and view all the answers

    What is the main characteristic of plasma that distinguishes it from a gas?

    <p>It is electrically conductive</p> Signup and view all the answers

    What is the characteristic of atoms in a Bose-Einstein condensate?

    <p>Super unexcited and super cold</p> Signup and view all the answers

    Which of the following is an example of plasma?

    <p>Flame and lightning</p> Signup and view all the answers

    What is the temperature at which the first Bose-Einstein condensate was produced?

    <p>170 nanokelvins</p> Signup and view all the answers

    What is the correct statement about the particles in plasma?

    <p>They are charged and respond strongly to electromagnetic fields</p> Signup and view all the answers

    What is the term used to describe plasma?

    <p>Ionized gas</p> Signup and view all the answers

    Who predicted the existence of Bose-Einstein condensate in the 1920s?

    <p>Satyendra Bose and Albert Einstein</p> Signup and view all the answers

    What is the main reason why plasma is electrically conductive?

    <p>Because it consists of charged particles</p> Signup and view all the answers

    What is the opposite of super-hot and super excited atoms?

    <p>Super unexcited and super cold atoms</p> Signup and view all the answers

    What happens when atoms take up the same place in a Bose-Einstein condensate?

    <p>They become a single entity</p> Signup and view all the answers

    Which of the following statements about plasma is false?

    <p>Plasma has a definite volume and shape</p> Signup and view all the answers

    What is the state of matter characterized by atoms being in a state of random continuous motion?

    <p>Gas</p> Signup and view all the answers

    What is the correct statement about evaporation and cooling?

    <p>Evaporation causes cooling</p> Signup and view all the answers

    What is the composition of a mixture?

    <p>Variable</p> Signup and view all the answers

    What happens when common salt is dissolved in water?

    <p>A mixture is formed</p> Signup and view all the answers

    What is a characteristic of a mixture?

    <p>It does not have a fixed melting or boiling point</p> Signup and view all the answers

    What is steel used to make?

    <p>Rust-free, unbreakable utensils</p> Signup and view all the answers

    What is bone an example of?

    <p>A composite material</p> Signup and view all the answers

    What is wood composed of?

    <p>Cellulose mixed with lignin</p> Signup and view all the answers

    What is a composite material?

    <p>A material that combines the properties of two constituents</p> Signup and view all the answers

    What is the purpose of creating composite materials?

    <p>To get the exact properties needed for a particular job</p> Signup and view all the answers

    What is the characteristic of a mixture that makes it different from a pure substance?

    <p>It does not have a fixed composition</p> Signup and view all the answers

    What is the fundamental characteristic of a pure substance?

    <p>It is uniform or homogeneous throughout.</p> Signup and view all the answers

    What is the difference between an element and a compound?

    <p>An element is made up of only one kind of atom, while a compound is made up of only one kind of molecule.</p> Signup and view all the answers

    What is a characteristic of particles in a pure substance?

    <p>They are similar to one another.</p> Signup and view all the answers

    What is a mixture?

    <p>A material that contains two or more different kinds of particles which do not react chemically but are physically mixed in any proportion.</p> Signup and view all the answers

    What is the characteristic of a pure substance that makes it impossible to be separated into simpler particles?

    <p>It cannot be separated into simpler particles by physical processes.</p> Signup and view all the answers

    What is the term for the components or constituents of a mixture?

    <p>Pure substances</p> Signup and view all the answers

    What is the difference between a pure substance and a mixture?

    <p>A pure substance is made up of only one kind of particles, while a mixture is made up of two or more different kinds of particles.</p> Signup and view all the answers

    What is the characteristic of water that makes it a pure substance?

    <p>It has uniform composition throughout.</p> Signup and view all the answers

    What is the characteristic of a mixture?

    <p>It has a variable composition</p> Signup and view all the answers

    What is a characteristic of a composite material?

    <p>It combines the properties of two constituents</p> Signup and view all the answers

    What is steel used to make?

    <p>Rust-free utensils</p> Signup and view all the answers

    What is bone composed of?

    <p>Cellulose and lignin</p> Signup and view all the answers

    What is wood composed of?

    <p>Cellulose and lignin</p> Signup and view all the answers

    What is the difference between a mixture and a composite material?

    <p>A mixture has a variable composition, while a composite material has a fixed composition</p> Signup and view all the answers

    What is a characteristic of a pure substance?

    <p>It has a fixed melting point</p> Signup and view all the answers

    What is an example of a composite material?

    <p>All of the above</p> Signup and view all the answers

    What is the main difference between a mixture and a composite material?

    <p>A mixture has a variable composition, while a composite material has a fixed composition</p> Signup and view all the answers

    What is the characteristic of a pure substance?

    <p>It is uniform or homogenous throughout.</p> Signup and view all the answers

    What is the difference between an element and a compound?

    <p>An element is made up of atoms, while a compound is made up of molecules.</p> Signup and view all the answers

    What is the characteristic of particles in a pure substance?

    <p>They are similar to one another.</p> Signup and view all the answers

    What is a mixture?

    <p>A material that contains two or more different kinds of particles.</p> Signup and view all the answers

    What is the characteristic of a pure substance in terms of its composition?

    <p>It has a uniform composition.</p> Signup and view all the answers

    What is the main difference between a pure substance and a mixture?

    <p>A pure substance is uniform or homogenous, while a mixture is physically mixed.</p> Signup and view all the answers

    What is an example of a pure substance?

    <p>Water.</p> Signup and view all the answers

    What is the term for the components of a mixture?

    <p>Constituents.</p> Signup and view all the answers

    What is the characteristic of a pure substance?

    <p>It is uniform or homogenous throughout</p> Signup and view all the answers

    What is an element?

    <p>A pure substance made up of only one kind of atom</p> Signup and view all the answers

    What is a characteristic of particles in a pure substance?

    <p>They are similar to one another</p> Signup and view all the answers

    What is the term for the components of a mixture?

    <p>Constituents</p> Signup and view all the answers

    What is a characteristic of a mixture?

    <p>It contains two or more different kinds of particles</p> Signup and view all the answers

    What is the difference between an element and a compound?

    <p>An element is made up of only one kind of atom, while a compound is made up of only one kind of molecule</p> Signup and view all the answers

    Why is water considered a pure substance?

    <p>Because it has uniform composition throughout</p> Signup and view all the answers

    What is not a characteristic of a mixture?

    <p>It is uniform or homogenous throughout</p> Signup and view all the answers

    What is the definition of a mixture?

    <p>A substance with a variable composition</p> Signup and view all the answers

    What is a characteristic of a mixture?

    <p>It has a variable composition</p> Signup and view all the answers

    What is a composite material?

    <p>A material that combines the properties of two constituents</p> Signup and view all the answers

    What is steel used to make?

    <p>Unbreakable utensils</p> Signup and view all the answers

    What is bone an example of?

    <p>A composite material</p> Signup and view all the answers

    What is wood composed of?

    <p>Cellulose mixed with lignin</p> Signup and view all the answers

    What is the difference between a mixture and a pure substance?

    <p>A mixture has a variable composition, while a pure substance has a fixed composition</p> Signup and view all the answers

    What is a characteristic of a composite material?

    <p>It combines the properties of two or more constituents</p> Signup and view all the answers

    What is the primary reason for creating a composite material?

    <p>To achieve specific properties needed for a particular job</p> Signup and view all the answers

    What was Antoine Lavoisier's contribution to the field of chemistry?

    <p>He gave a useful definition of an element</p> Signup and view all the answers

    What is the modern definition of an element?

    <p>A pure substance that contains only one kind of atoms</p> Signup and view all the answers

    How many elements have been discovered so far?

    <p>118</p> Signup and view all the answers

    What is the state of matter of most elements at room temperature?

    <p>Solid</p> Signup and view all the answers

    Which two elements are known to exist in the liquid state at room temperature?

    <p>Mercury and bromine</p> Signup and view all the answers

    What is the characteristic of atoms of the same element?

    <p>They are identical in all respects</p> Signup and view all the answers

    Why was Antoine Lavoisier's definition of an element not considered absolutely correct?

    <p>Elements can be broken into simpler substances and synthesized from other elements</p> Signup and view all the answers

    What is the main difference between atoms of different elements?

    <p>They have different sizes and masses</p> Signup and view all the answers

    What is the temperature at which gallium and caesium become liquid?

    <p>Slightly above room temperature</p> Signup and view all the answers

    Which of the following elements are gaseous at room temperature?

    <p>All of the above</p> Signup and view all the answers

    What is a characteristic of metals?

    <p>They are malleable and can be formed into thin sheets</p> Signup and view all the answers

    Which of the following metals are the most malleable?

    <p>Gold and silver</p> Signup and view all the answers

    How many types of elements are classified based on physical properties?

    <p>3</p> Signup and view all the answers

    What is a characteristic of non-metals?

    <p>They are brittle and do not conduct electricity</p> Signup and view all the answers

    Which of the following elements is not a metal?

    <p>Fluorine</p> Signup and view all the answers

    What is the classification of elements based on physical properties?

    <p>Metals, non-metals, and metalloids</p> Signup and view all the answers

    What is unique about the properties of gallium and caesium?

    <p>They both become liquid at a relatively low temperature</p> Signup and view all the answers

    Who is credited with giving a useful definition of an element?

    <p>Antoine Laurent Lavoisier</p> Signup and view all the answers

    What is the current definition of an element?

    <p>A pure substance that contains only one kind of atoms</p> Signup and view all the answers

    How many elements have been discovered so far?

    <p>118</p> Signup and view all the answers

    What is the state of majority of the elements at room temperature?

    <p>Solid</p> Signup and view all the answers

    Which two elements are known to exist in the liquid state at room temperature?

    <p>Mercury and bromine</p> Signup and view all the answers

    What is the characteristic of atoms of the same element?

    <p>They are identical in all respects, size, mass, and composition</p> Signup and view all the answers

    What was the limitation of the original definition of an element given by Antoine Laurent Lavoisier?

    <p>It was proved wrong by the discovery of radioactivity</p> Signup and view all the answers

    Who was the first scientist to use the term 'element'?

    <p>Robert Boyle</p> Signup and view all the answers

    At what temperature do gallium and caesium become liquid?

    <p>Slightly above room temperature (303 K)</p> Signup and view all the answers

    What are the three types of elements classified based on physical properties?

    <p>Metals, Non-metals, and Metalloids</p> Signup and view all the answers

    What is malleability a characteristic of?

    <p>Metals</p> Signup and view all the answers

    Which of the following elements are the most malleable?

    <p>Gold and Silver</p> Signup and view all the answers

    How many elements are gaseous at room temperature?

    <p>11</p> Signup and view all the answers

    What are the names of the two most malleable metals?

    <p>Silver and Gold</p> Signup and view all the answers

    What is the characteristic of metals that means they can be hammered or beaten into thin sheets?

    <p>Malleability</p> Signup and view all the answers

    What type of elements are hydrogen, oxygen, and nitrogen?

    <p>Gases</p> Signup and view all the answers

    Which of the following elements are NOT gaseous at room temperature?

    <p>Gold and Silver</p> Signup and view all the answers

    What is the primary use of silver foil?

    <p>For decorating sweets</p> Signup and view all the answers

    What does the ductility of metals mean?

    <p>Metals can be drawn or stretched into thin wires</p> Signup and view all the answers

    Which metal is the best conductor of electricity?

    <p>Silver</p> Signup and view all the answers

    What is the characteristic of metals that makes them good reflectors?

    <p>Their shining surface</p> Signup and view all the answers

    Why are metals like sodium and potassium soft?

    <p>Because they are naturally soft</p> Signup and view all the answers

    What is the characteristic of metals that makes them hold large weights without breaking?

    <p>Their high tensile strength</p> Signup and view all the answers

    What is the use of aluminium foils in packaging?

    <p>For wrapping medicines and food items</p> Signup and view all the answers

    What is the characteristic of metals that makes them good conductors of heat?

    <p>Their high thermal conductivity</p> Signup and view all the answers

    Which metal is the poorest conductor of heat?

    <p>Lead</p> Signup and view all the answers

    Why are metals like gold and silver used for making jewellery?

    <p>Because they are ductile and lustrous</p> Signup and view all the answers

    What is a characteristic of metals?

    <p>Having a high tensile strength</p> Signup and view all the answers

    Which of the following metals is not strong?

    <p>Sodium</p> Signup and view all the answers

    What is a common use of metals due to their sonorous property?

    <p>Making musical instruments</p> Signup and view all the answers

    What is a characteristic of non-metals?

    <p>Being brittle and breaking easily</p> Signup and view all the answers

    Which of the following non-metals is a good conductor of heat and electricity?

    <p>Graphite</p> Signup and view all the answers

    What is a common characteristic of metals?

    <p>Having a high density</p> Signup and view all the answers

    Which of the following metals is a liquid at room temperature?

    <p>Mercury</p> Signup and view all the answers

    What is a characteristic of non-metals that makes them useful as insulators?

    <p>Their ability to resist heat and electricity</p> Signup and view all the answers

    What is the general trend in the melting and boiling points of metals?

    <p>They are generally high</p> Signup and view all the answers

    What is a characteristic of metals that makes them suitable for construction?

    <p>Their high tensile strength</p> Signup and view all the answers

    What is a characteristic of metals?

    <p>Being sonorous</p> Signup and view all the answers

    What is true about sodium and potassium metals?

    <p>They are not strong and have low tensile strength</p> Signup and view all the answers

    What is a characteristic of non-metals?

    <p>Being bad conductors of heat and electricity</p> Signup and view all the answers

    What is graphite used for?

    <p>Making electrodes of batteries and dry cells</p> Signup and view all the answers

    What is true about mercury?

    <p>It is a liquid at room temperature</p> Signup and view all the answers

    What is a characteristic of metals?

    <p>Having high densities</p> Signup and view all the answers

    What is a characteristic of non-metals?

    <p>Being soft</p> Signup and view all the answers

    What is a characteristic of gallium and caesium?

    <p>They become liquid at a temperature slightly above room temperature</p> Signup and view all the answers

    What is an exception to non-metals being bad conductors of heat and electricity?

    <p>All of the above</p> Signup and view all the answers

    What is steel?

    <p>An alloy of iron and carbon</p> Signup and view all the answers

    What is the primary use of silver foil?

    <p>For decorating sweets</p> Signup and view all the answers

    Which metal can be drawn into a wire of about 2 kilometre length with just 1 gram of it?

    <p>Gold</p> Signup and view all the answers

    What is the best conductor of heat among metals?

    <p>Silver</p> Signup and view all the answers

    Which metal is an excellent reflector of light and is used for silvering of mirrors?

    <p>Silver</p> Signup and view all the answers

    What is the property of metals that allows them to hold large weights without breaking?

    <p>High tensile strength</p> Signup and view all the answers

    Which metal is the poorest conductor of heat?

    <p>Lead</p> Signup and view all the answers

    What is the characteristic of metals that allows them to be shaped into thin wires or sheets?

    <p>Ductility</p> Signup and view all the answers

    Which metal is the best conductor of electricity?

    <p>Silver</p> Signup and view all the answers

    What is the general characteristic of metals regarding their hardness?

    <p>They are generally hard, but some are soft</p> Signup and view all the answers

    Which metal is used for making milk bottle caps?

    <p>Aluminium</p> Signup and view all the answers

    What is the characteristic of non-metals that makes them different from metals?

    <p>They have low tensile strength and are not sonorous</p> Signup and view all the answers

    Which of the following is NOT a characteristic of non-metals?

    <p>They are good conductors of electricity</p> Signup and view all the answers

    What is the term for elements that have properties in between those of metals and non-metals?

    <p>Metalloids</p> Signup and view all the answers

    What is the definition of a compound?

    <p>A pure substance made up of two or more elements chemically combined in a fixed proportion by mass</p> Signup and view all the answers

    What is the state of matter of bromine at room temperature?

    <p>Liquid</p> Signup and view all the answers

    What is the hardest natural substance known?

    <p>Diamond</p> Signup and view all the answers

    What is the characteristic of metalloids that makes them different from metals and non-metals?

    <p>They are brittle like non-metals</p> Signup and view all the answers

    What is the characteristic of non-metals that makes them different from metals in terms of their physical states?

    <p>They exist in all three states of matter</p> Signup and view all the answers

    What is the characteristic of solid non-metals, except for boron, graphite, and diamond?

    <p>They have low melting and boiling points</p> Signup and view all the answers

    What is the characteristic of non-metals in terms of their density?

    <p>They have low densities</p> Signup and view all the answers

    What is a characteristic of a compound?

    <p>It is made up of different elements combined in a fixed proportion by mass.</p> Signup and view all the answers

    What is necessary for a compound to be formed?

    <p>A chemical reaction between elements.</p> Signup and view all the answers

    What is unique about the properties of a compound?

    <p>They are entirely different from those of its constituent elements.</p> Signup and view all the answers

    What is an example of a compound?

    <p>Iron sulphide.</p> Signup and view all the answers

    What happens when iron sulphide reacts with dilute sulphuric acid?

    <p>Hydrogen sulphide gas is formed.</p> Signup and view all the answers

    What is the difference between iron sulphide and its constituent elements?

    <p>Iron sulphide has different properties from iron and sulphur.</p> Signup and view all the answers

    What is the result of heating a mixture of iron and sulphur?

    <p>A chemical reaction occurs, forming iron sulphide.</p> Signup and view all the answers

    What is a characteristic of a chemical compound?

    <p>It is formed by a chemical reaction.</p> Signup and view all the answers

    What is the difference between a mixture and a compound?

    <p>A compound has properties that are different from its constituent elements.</p> Signup and view all the answers

    What is an example of a chemical compound that is commonly used?

    <p>All of the above.</p> Signup and view all the answers

    What is the primary condition for the formation of water from hydrogen and oxygen?

    <p>Passing an electric spark through the mixture</p> Signup and view all the answers

    What is a characteristic of a compound that distinguishes it from its constituent elements?

    <p>It has different properties from its constituent elements</p> Signup and view all the answers

    What is the process by which a compound can be separated into its constituent elements?

    <p>Electrolysis</p> Signup and view all the answers

    What is a characteristic of a compound that makes it a homogeneous substance?

    <p>It has the same properties throughout</p> Signup and view all the answers

    What is a criterion of purity of a solid compound?

    <p>It has a sharp melting point</p> Signup and view all the answers

    What is a characteristic of a compound that is involved in its formation?

    <p>A chemical bond is formed</p> Signup and view all the answers

    What is the result of impurities in a solid compound?

    <p>The melting point is decreased</p> Signup and view all the answers

    What is a characteristic of a compound that is evident in its physical properties?

    <p>It has a fixed melting point</p> Signup and view all the answers

    What is the result of electrolysis of a compound?

    <p>The compound is separated into its constituent elements</p> Signup and view all the answers

    What is a characteristic of a compound that distinguishes it from a mixture?

    <p>It is a homogeneous substance</p> Signup and view all the answers

    What is the boiling point of pure water at one atmosphere pressure?

    <p>100'C (373K)</p> Signup and view all the answers

    Why is ocean water not drinkable and cannot be used for crop irrigation?

    <p>It contains a large number of dissolved compounds</p> Signup and view all the answers

    What is the characteristic of a homogeneous mixture?

    <p>It has a uniform composition throughout</p> Signup and view all the answers

    What is an example of a heterogeneous mixture?

    <p>Milk</p> Signup and view all the answers

    What is the term for a mixture of two or more metals in the solid phase?

    <p>Alloy</p> Signup and view all the answers

    What is the characteristic of the components of a heterogeneous mixture?

    <p>They are visible to the naked eye or under a microscope</p> Signup and view all the answers

    Why is sea water's boiling point higher than 100'C (373K)?

    <p>It contains several dissolved salts</p> Signup and view all the answers

    What is the characteristic of all homogeneous mixtures?

    <p>They have a uniform composition throughout</p> Signup and view all the answers

    What is the difference between a homogeneous mixture and a heterogeneous mixture?

    <p>The composition of the mixture</p> Signup and view all the answers

    What is an example of a homogeneous mixture in the solid phase?

    <p>Alloys</p> Signup and view all the answers

    What happens when hydrogen and oxygen are simply mixed?

    <p>No reaction occurs</p> Signup and view all the answers

    What is a characteristic of a compound?

    <p>It has a fixed melting point and boiling point</p> Signup and view all the answers

    Why does water extinguish fire?

    <p>Because it is neither combustible nor a supporter of combustion</p> Signup and view all the answers

    How can a compound be separated into its constituents?

    <p>By chemical means, such as electrolysis</p> Signup and view all the answers

    What is a characteristic of a pure solid compound?

    <p>It has a sharp melting point</p> Signup and view all the answers

    What is required for elements to become a compound?

    <p>A chemical bond between the atoms of elements</p> Signup and view all the answers

    What is a characteristic of a liquid compound?

    <p>It has a fixed boiling point</p> Signup and view all the answers

    What is the main reason why the boiling point of sea water is higher than that of pure water?

    <p>Because sea water contains dissolved salts and other impurities</p> Signup and view all the answers

    What is the result of chemical bonding between elements?

    <p>A compound with properties different from its constituents</p> Signup and view all the answers

    What is a characteristic of a compound?

    <p>It is a homogeneous substance</p> Signup and view all the answers

    What is the term used to describe a mixture that has a uniform composition throughout?

    <p>Homogeneous mixture</p> Signup and view all the answers

    What is the result of energy being evolved or absorbed during the formation of a compound?

    <p>A chemical bond between the atoms of elements</p> Signup and view all the answers

    What is the term used to describe a mixture that does not have a uniform composition throughout?

    <p>Heterogeneous mixture</p> Signup and view all the answers

    What is an example of a homogeneous mixture in the solid phase?

    <p>All of the above</p> Signup and view all the answers

    Why is ocean water not suitable for drinking or irrigation?

    <p>Because it contains dissolved salts and other impurities</p> Signup and view all the answers

    What is the term used to describe a mixture of two or more miscible liquids?

    <p>Homogeneous mixture</p> Signup and view all the answers

    Why is rainwater considered a pure substance?

    <p>Because it contains dissolved gases from the air</p> Signup and view all the answers

    What is the term used to describe a mixture of two or more metals?

    <p>Alloy</p> Signup and view all the answers

    Why do homogeneous mixtures have a uniform composition throughout?

    <p>Because they have a single phase</p> Signup and view all the answers

    What is the main difference between homogeneous and heterogeneous mixtures?

    <p>Their composition throughout</p> Signup and view all the answers

    What is the main distinction between a pure substance and a mixture?

    <p>A pure substance has a fixed composition, while a mixture does not.</p> Signup and view all the answers

    What is an example of a heterogeneous mixture?

    <p>A mixture of salt and sand</p> Signup and view all the answers

    Why is a salt solution considered a mixture?

    <p>Because its constituents can be separated by physical processes</p> Signup and view all the answers

    What is a characteristic of a mixture?

    <p>Its composition can vary</p> Signup and view all the answers

    Why is helium considered a pure substance?

    <p>Because it is an element</p> Signup and view all the answers

    What is an example of a container filled with a pure substance rather than with a mixture?

    <p>A balloon filled with helium</p> Signup and view all the answers

    Why is a salt solution homogeneous?

    <p>Because it appears uniform</p> Signup and view all the answers

    What is a characteristic of a compound?

    <p>It has a fixed composition</p> Signup and view all the answers

    Why can a mixture be separated by physical processes?

    <p>Because its constituents are separable by physical processes</p> Signup and view all the answers

    What is a difference between a mixture and a compound?

    <p>A mixture has a variable composition, while a compound has a fixed composition</p> Signup and view all the answers

    Study Notes

    What is Chemistry?

    • Chemistry is the study of the composition, properties, and reactions of matter
    • It involves understanding what matter is, how it behaves, and how it changes

    What is Matter?

    • Matter refers to all substances and materials that make up the physical universe
    • It has three fundamental properties: mass, occupying space, and inertia

    Properties of Matter

    • Mass: the amount of matter in an object, which determines its weight
      • Example: a larger brick weighs more than a smaller brick because it contains more matter
    • Occupies Space: matter takes up space and cannot be occupied by other matter simultaneously
      • Example: two stools cannot occupy the same corner of a room, and two trucks cannot pass each other in a narrow lane
    • Inertia: matter resists changes in its motion or position unless acted upon by an external force
      • Example: a football will remain stationary until pushed, and will continue moving until stopped by an external force

    What is Chemistry?

    • Chemistry is the study of the composition, properties, and reactions of matter
    • It involves understanding what matter is, how it behaves, and how it changes

    What is Matter?

    • Matter refers to all substances and materials that make up the physical universe
    • It has three fundamental properties: mass, occupying space, and inertia

    Properties of Matter

    • Mass: the amount of matter in an object, which determines its weight
      • Example: a larger brick weighs more than a smaller brick because it contains more matter
    • Occupies Space: matter takes up space and cannot be occupied by other matter simultaneously
      • Example: two stools cannot occupy the same corner of a room, and two trucks cannot pass each other in a narrow lane
    • Inertia: matter resists changes in its motion or position unless acted upon by an external force
      • Example: a football will remain stationary until pushed, and will continue moving until stopped by an external force

    Gravity and Matter

    • Gravity is the force of attraction exerted by the Earth on objects, causing them to fall towards the ground.
    • The force of gravity affects everything with mass, including objects thrown upwards, which will eventually come back down to the ground.
    • Gravity is responsible for fruits falling from trees and objects having weight.

    Conservation of Mass

    • Matter cannot be destroyed or created, only transformed from one form to another.
    • The total mass of matter remains the same before and after physical and chemical changes.
    • This is demonstrated by Lavoisier's experiment, where tin metal was heated and converted into tin oxide, with the total weight remaining unchanged.

    Characteristics of Matter

    • Matter is defined as anything that has mass and occupies space.
    • Things that don't have mass or occupy space, such as heat, light, sound, electricity, and shadows, are not considered matter.
    • To determine if something is matter, check if it has weight; if it doesn't, it's not matter.

    Particles of Matter

    • All substances, including solids, liquids, and gases, are made up of constantly moving molecules, atoms, or ions.
    • The kinetic energy of these particles determines their physical behavior.
    • Evidence for particle movement includes the zig-zag motion of pollen grains in water.

    Gravity and Matter

    • Gravity is the force of attraction exerted by the Earth on objects, causing them to fall towards the ground.
    • The force of gravity affects everything with mass, including objects thrown upwards, which will eventually come back down to the ground.
    • Gravity is responsible for fruits falling from trees and objects having weight.

    Conservation of Mass

    • Matter cannot be destroyed or created, only transformed from one form to another.
    • The total mass of matter remains the same before and after physical and chemical changes.
    • This is demonstrated by Lavoisier's experiment, where tin metal was heated and converted into tin oxide, with the total weight remaining unchanged.

    Characteristics of Matter

    • Matter is defined as anything that has mass and occupies space.
    • Things that don't have mass or occupy space, such as heat, light, sound, electricity, and shadows, are not considered matter.
    • To determine if something is matter, check if it has weight; if it doesn't, it's not matter.

    Particles of Matter

    • All substances, including solids, liquids, and gases, are made up of constantly moving molecules, atoms, or ions.
    • The kinetic energy of these particles determines their physical behavior.
    • Evidence for particle movement includes the zig-zag motion of pollen grains in water.

    Brownian Motion

    • The zig-zag movement of small particles suspended in a liquid or gas due to constant collisions with fast-moving particles is called Brownian motion.
    • Brownian motion increases with temperature due to increased kinetic energy of particles of matter.

    States of Matter

    • Solids change into liquids and liquids into gases when particles gain more kinetic energy, allowing them to move apart from one another.
    • When molecules vibrate more quickly upon heating, some of them escape from the matter.

    Kinetic Molecular Theory of Matter

    • This theory states that any substance, whether solid, liquid, or gas, is made up of atoms, molecules, or ions that are in constant motion.
    • The main postulates of the kinetic theory of matter are:
      • Matter consists of molecules that are capable of free existence and retain all the chemical properties of the parent substance.
      • Molecules are always in a state of random continuous motion.
      • Molecules exert forces on one another, depending on intermolecular distances.
      • All collisions between particles of matter are perfectly elastic.
    • In solids, molecules vibrate about their average position.
    • In liquids, particles have enough free space to move about, but they still attract each other.
    • In gases, particles move about randomly, possessing kinetic energy.

    Particle Movement

    • Particles, especially in the gaseous or liquid state, move in a random (Helter-Skelter) direction.
    • Particles collide with one another elastically, with the total energy of the colliding particles remaining the same.
    • The movement is caused by the force of attraction between molecules, known as intermolecular force.

    Experiment: Diffusion of Iodine

    • The experiment demonstrates the mobility of particles of matter.
    • Iodine particles spread throughout the test tube, indicating their mobile nature.
    • The presence of iodine at the mouth of the test tube is detected using starch iodide paper, which turns blue.

    Experiment to Demonstrate Particle Mobility

    • A simple experiment involves placing a small piece of iodine in a corked glass test tube, which releases violet vapors of iodine that spread throughout the test tube.
    • When a starch iodide paper is brought near the mouth of the test tube, it turns blue, indicating the presence of iodine particles.

    Diffusion and Kinetic Molecular Theory

    • The diffusion of iodine particles demonstrates that particles are mobile and can move and spread in a confined space.
    • The kinetic molecular theory of matter explains that particles have kinetic energy, which enables them to move and mix with other particles.
    • When salt and water come into contact, their molecules mix and spread due to their kinetic energy, resulting in a uniform salty taste throughout the container.

    States of Matter and Kinetic Theory

    • The three states of matter (solids, liquids, and gases) differ in their particle packing, energy, and intermolecular forces.

    Characteristics of Solids

    • Particles are closely packed and have fixed positions.
    • Particles can only vibrate to and fro about their mean position, resulting in small energy due to motion.
    • Strong intermolecular forces hold particles together, giving solids a definite shape and volume.
    • Solids are:
      • Incompressible and highly rigid
      • Have high density
      • Do not flow (non-fluid)

    Experiment to Demonstrate Particle Mobility

    • A simple experiment involves placing a small piece of iodine in a corked glass test tube, which releases violet vapors of iodine that spread throughout the test tube.
    • When a starch iodide paper is brought near the mouth of the test tube, it turns blue, indicating the presence of iodine particles.

    Diffusion and Kinetic Molecular Theory

    • The diffusion of iodine particles demonstrates that particles are mobile and can move and spread in a confined space.
    • The kinetic molecular theory of matter explains that particles have kinetic energy, which enables them to move and mix with other particles.
    • When salt and water come into contact, their molecules mix and spread due to their kinetic energy, resulting in a uniform salty taste throughout the container.

    States of Matter and Kinetic Theory

    • The three states of matter (solids, liquids, and gases) differ in their particle packing, energy, and intermolecular forces.

    Characteristics of Solids

    • Particles are closely packed and have fixed positions.
    • Particles can only vibrate to and fro about their mean position, resulting in small energy due to motion.
    • Strong intermolecular forces hold particles together, giving solids a definite shape and volume.
    • Solids are:
      • Incompressible and highly rigid
      • Have high density
      • Do not flow (non-fluid)

    Liquids

    • Particles are loosely packed and have no fixed positions
    • Particles have considerable energy due to their motion, allowing them to move freely
    • Intermolecular forces are strong enough to keep particles within the boundaries of the liquid
    • Liquids have a definite volume but no definite shape
    • Liquids are incompressible and not rigid
    • Density is relatively high compared to gases and lower than solids
    • Liquids flow from high to low levels due to fluidity

    Gases

    • Particles are widely spaced and have no fixed positions
    • Particles have maximum energy due to their motion, allowing them to move freely
    • Intermolecular forces are very weak, holding particles together
    • Gases have neither a definite shape nor a definite volume
    • Gases are highly compressible and not rigid
    • Density is very low
    • Gases can flow in any direction due to fluidity

    Liquids

    • Particles are loosely packed and have no fixed positions
    • Particles have considerable energy due to their motion, allowing them to move freely
    • Intermolecular forces are strong enough to keep particles within the boundaries of the liquid
    • Liquids have a definite volume but no definite shape
    • Liquids are incompressible and not rigid
    • Density is relatively high compared to gases and lower than solids
    • Liquids flow from high to low levels due to fluidity

    Gases

    • Particles are widely spaced and have no fixed positions
    • Particles have maximum energy due to their motion, allowing them to move freely
    • Intermolecular forces are very weak, holding particles together
    • Gases have neither a definite shape nor a definite volume
    • Gases are highly compressible and not rigid
    • Density is very low
    • Gases can flow in any direction due to fluidity

    Characteristics of Solids

    • A wooden block is considered a solid because it has a fixed shape and is rigid, following all properties of a solid.
    • A rubber band is also considered a solid, despite changing shape when stretched, because it regains its original shape when the force is removed.

    Kinetic Model of a Solid

    • In a solid, molecules are closely packed, with negligible intermolecular space.
    • Molecules have fixed positions, with negligible movement.
    • Molecules are arranged in a definite manner.
    • There is a strong force of attraction (intermolecular force) between molecules.

    Kinetic Model of a Liquid

    • In a liquid, molecules are far apart from each other, with greater intermolecular space than in a solid.
    • The intermolecular force of attraction between molecules is not strong enough to keep them bonded to one position.
    • Molecules can move about more freely, with irregular and random motion.

    Characteristics of Solids

    • A wooden block is considered a solid because it has a fixed shape and is rigid, following all properties of a solid.
    • A rubber band is also considered a solid, despite changing shape when stretched, because it regains its original shape when the force is removed.

    Kinetic Model of a Solid

    • In a solid, molecules are closely packed, with negligible intermolecular space.
    • Molecules have fixed positions, with negligible movement.
    • Molecules are arranged in a definite manner.
    • There is a strong force of attraction (intermolecular force) between molecules.

    Kinetic Model of a Liquid

    • In a liquid, molecules are far apart from each other, with greater intermolecular space than in a solid.
    • The intermolecular force of attraction between molecules is not strong enough to keep them bonded to one position.
    • Molecules can move about more freely, with irregular and random motion.

    Surface Tension

    • Surface tension is a property of liquids due to intermolecular forces between liquid particles.
    • Liquid surface feels stretched due to surface tension.
    • Molecules in the bulk of the liquid are attracted equally on all sides, while surface molecules are subjected only to downward attractive forces.
    • This creates an imbalance of forces at the surface, resulting in surface tension.
    • Surface tension decreases with a rise in temperature.
    • The decrease in surface tension is due to increased kinetic energy of molecules, leading to decreased intermolecular forces.

    Surface Tension and Nature of Liquid

    • Surface tension is a measure of intermolecular attractive forces.
    • When attractive forces between molecules are large, surface tension is also large.
    • For example, the surface tension of a liquid is higher when the intermolecular forces are stronger.

    Viscosity

    • Viscosity is the internal friction or resistance that resists the relative motion of a liquid.
    • It is caused by molecular forces working between the molecules of the liquid.
    • Viscosity depends on the cohesive force between molecules.
    • Glycerine has more viscosity than water or alcohol due to stronger intermolecular forces.

    Viscosity and Nature of Liquid

    • Viscosity is related to the intermolecular forces in the liquid.
    • If intermolecular forces are large, viscosity will be high.
    • For example, honey is more viscous than water because of stronger intermolecular forces.

    Effect of Temperature on Viscosity

    • Viscosity of a liquid decreases with a rise in temperature.
    • As temperature increases, average kinetic energy increases, and intermolecular forces can be easily overcome.
    • Therefore, the liquid starts moving faster with increased temperature.

    Surface Tension

    • Surface tension is a property of liquids due to intermolecular forces between liquid particles.
    • Liquid surface feels stretched due to surface tension.
    • Molecules in the bulk of the liquid are attracted equally on all sides, while surface molecules are subjected only to downward attractive forces.
    • This creates an imbalance of forces at the surface, resulting in surface tension.
    • Surface tension decreases with a rise in temperature.
    • The decrease in surface tension is due to increased kinetic energy of molecules, leading to decreased intermolecular forces.

    Surface Tension and Nature of Liquid

    • Surface tension is a measure of intermolecular attractive forces.
    • When attractive forces between molecules are large, surface tension is also large.
    • For example, the surface tension of a liquid is higher when the intermolecular forces are stronger.

    Viscosity

    • Viscosity is the internal friction or resistance that resists the relative motion of a liquid.
    • It is caused by molecular forces working between the molecules of the liquid.
    • Viscosity depends on the cohesive force between molecules.
    • Glycerine has more viscosity than water or alcohol due to stronger intermolecular forces.

    Viscosity and Nature of Liquid

    • Viscosity is related to the intermolecular forces in the liquid.
    • If intermolecular forces are large, viscosity will be high.
    • For example, honey is more viscous than water because of stronger intermolecular forces.

    Effect of Temperature on Viscosity

    • Viscosity of a liquid decreases with a rise in temperature.
    • As temperature increases, average kinetic energy increases, and intermolecular forces can be easily overcome.
    • Therefore, the liquid starts moving faster with increased temperature.

    Surface Tension

    • Surface tension is a property of liquids due to intermolecular forces between liquid particles.
    • Liquid surface feels stretched due to surface tension.
    • Molecules in the bulk of the liquid are attracted equally on all sides, while surface molecules are subjected only to downward attractive forces.
    • This creates an imbalance of forces at the surface, resulting in surface tension.
    • Surface tension decreases with a rise in temperature.
    • The decrease in surface tension is due to increased kinetic energy of molecules, leading to decreased intermolecular forces.

    Surface Tension and Nature of Liquid

    • Surface tension is a measure of intermolecular attractive forces.
    • When attractive forces between molecules are large, surface tension is also large.
    • For example, the surface tension of a liquid is higher when the intermolecular forces are stronger.

    Viscosity

    • Viscosity is the internal friction or resistance that resists the relative motion of a liquid.
    • It is caused by molecular forces working between the molecules of the liquid.
    • Viscosity depends on the cohesive force between molecules.
    • Glycerine has more viscosity than water or alcohol due to stronger intermolecular forces.

    Viscosity and Nature of Liquid

    • Viscosity is related to the intermolecular forces in the liquid.
    • If intermolecular forces are large, viscosity will be high.
    • For example, honey is more viscous than water because of stronger intermolecular forces.

    Effect of Temperature on Viscosity

    • Viscosity of a liquid decreases with a rise in temperature.
    • As temperature increases, average kinetic energy increases, and intermolecular forces can be easily overcome.
    • Therefore, the liquid starts moving faster with increased temperature.

    Properties of Bromine

    • Bromine has a melting point of -7.2°C and a boiling point of 59°C.
    • At a temperature greater than -7.2°C but less than 59°C, bromine is a liquid, having a definite volume but no definite shape.

    Kinetic Model of a Gas

    • In a gas, molecules are spaced far apart with negligible intermolecular forces, allowing them to move freely within the available space.
    • Gas molecules move rapidly, possessing high kinetic energy, and constantly collide with each other and the container walls.
    • These collisions cause the molecules to change direction and speed, exerting pressure on the container walls.

    Why Gases Fill Containers Completely

    • Gas molecules have large intermolecular spaces and high kinetic energy but weak intermolecular forces, allowing them to spread throughout the container.
    • This results in gases filling the entire space of their containing vessel.

    Important Properties of Gases

    Exertion of Pressure

    • Gases exert pressure in all directions due to the bombardment of particles against the container walls.

    Homogeneous Nature

    • Gases have a uniform composition throughout, making them homogeneous in nature.

    Liquefaction

    • Gases can be liquefied by cooling and applying pressure.

    Diffusion

    • Gases can diffuse and spread out to fill their containers.

    Properties of Bromine

    • Bromine has a melting point of -7.2°C and a boiling point of 59°C.
    • At a temperature greater than -7.2°C but less than 59°C, bromine is a liquid, having a definite volume but no definite shape.

    Kinetic Model of a Gas

    • In a gas, molecules are spaced far apart with negligible intermolecular forces, allowing them to move freely within the available space.
    • Gas molecules move rapidly, possessing high kinetic energy, and constantly collide with each other and the container walls.
    • These collisions cause the molecules to change direction and speed, exerting pressure on the container walls.

    Why Gases Fill Containers Completely

    • Gas molecules have large intermolecular spaces and high kinetic energy but weak intermolecular forces, allowing them to spread throughout the container.
    • This results in gases filling the entire space of their containing vessel.

    Important Properties of Gases

    Exertion of Pressure

    • Gases exert pressure in all directions due to the bombardment of particles against the container walls.

    Homogeneous Nature

    • Gases have a uniform composition throughout, making them homogeneous in nature.

    Liquefaction

    • Gases can be liquefied by cooling and applying pressure.

    Diffusion

    • Gases can diffuse and spread out to fill their containers.

    Diffusion of Gases

    • Gases have the property of intermixing with each other without mechanical aid, forming a homogeneous mixture called diffusion.
    • Examples of diffusion include the spread of ammonia smell in a laboratory and perfume smell in a room.

    Uses of Gaseous Diffusion

    • Separation of gases: lighter gases diffuse quickly than heavier gases, allowing for separation of gases from a mixture.
    • Determination of relative densities and molecular weights of gases using Graham's law of diffusion.

    States of Matter

    • There are three states of matter: solid, liquid, and gas.
    • These states are interconvertible, but require changes in conditions such as temperature and pressure.

    Interconversion of States of Matter

    • Changes in temperature:
      • Increasing temperature: solid to liquid to gas (e.g., ice to water to steam).
      • Decreasing temperature: gas to liquid to solid.
    • Changes in pressure:
      • Increasing pressure: gas to liquid to solid.
      • Decreasing pressure: solid to liquid to gas.

    Important Points

    • Not all substances can be converted from one state to another (e.g., sugar cannot be melted into liquid sugar).
    • Latent heat (hidden heat) is the energy required to change the state of a substance, which is absorbed without changing the temperature (e.g., heat required to melt ice).
    • Examples of changed states:
      • Ice to water to steam (heating).
      • Wax (solid) to wax (liquid) to wax vapor (heating).
      • Gases (e.g., nitrogen, oxygen, hydrogen, helium) to liquid state (cooling and increasing pressure).

    Diffusion of Gases

    • Gases have the property of intermixing with each other without mechanical aid, forming a homogeneous mixture called diffusion.
    • Examples of diffusion include the spread of ammonia smell in a laboratory and perfume smell in a room.

    Uses of Gaseous Diffusion

    • Separation of gases: lighter gases diffuse quickly than heavier gases, allowing for separation of gases from a mixture.
    • Determination of relative densities and molecular weights of gases using Graham's law of diffusion.

    States of Matter

    • There are three states of matter: solid, liquid, and gas.
    • These states are interconvertible, but require changes in conditions such as temperature and pressure.

    Interconversion of States of Matter

    • Changes in temperature:
      • Increasing temperature: solid to liquid to gas (e.g., ice to water to steam).
      • Decreasing temperature: gas to liquid to solid.
    • Changes in pressure:
      • Increasing pressure: gas to liquid to solid.
      • Decreasing pressure: solid to liquid to gas.

    Important Points

    • Not all substances can be converted from one state to another (e.g., sugar cannot be melted into liquid sugar).
    • Latent heat (hidden heat) is the energy required to change the state of a substance, which is absorbed without changing the temperature (e.g., heat required to melt ice).
    • Examples of changed states:
      • Ice to water to steam (heating).
      • Wax (solid) to wax (liquid) to wax vapor (heating).
      • Gases (e.g., nitrogen, oxygen, hydrogen, helium) to liquid state (cooling and increasing pressure).

    Diffusion of Gases

    • Gases have the property of intermixing with each other without mechanical aid to form a homogeneous mixture, called diffusion
    • Examples of diffusion include the smell of ammonia spreading in a laboratory and the smell of perfume spreading in a room
    • Diffusion can be used to separate gases from a mixture, as lighter gases diffuse faster than heavier gases

    Separation of Gases

    • Diffusion can be used to separate gases from a mixture by repeating the process of diffusion
    • This process takes advantage of the difference in rates of diffusion between lighter and heavier gases

    States of Matter

    • The three states of matter are solid, liquid, and gas
    • These states are interconvertible, meaning they can be changed from one state to another and back again
    • Changes in temperature and pressure can cause these conversions

    Changes of State

    • Changes in temperature and pressure can cause changes in state
    • Examples include:
      • Ice (solid) → water (liquid) by heating above 0°C
      • Water (liquid) → vapour (gas) by heating above 100°C
      • Wax (solid) → molten wax (liquid) by heating
      • Molten wax (liquid) → wax vapour (gas) by further heating
      • Gas → liquid → solid by cooling and increasing pressure

    Latent Heat

    • Latent heat is the energy required to change the state of a substance (e.g., from solid to liquid)
    • During a change of state, the temperature of the system remains constant until all of the substance has changed state
    • The energy supplied during this process is used to break the intermolecular forces of attraction holding the substance in its original state
    • The term "latent" means "hidden" because the energy is not visible as a change in temperature

    Latent Heat

    • There are two types of latent heat: latent heat of fusion and latent heat of vaporization

    Latent Heat of Fusion

    • Defined as the amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure without any change in temperature at its melting point
    • Latent heat of fusion of ice is 3.34 x 10^5 J/kg

    Melting Process

    • When a solid is heated, molecules absorb heat energy, increasing kinetic energy and temperature
    • Further heat energy is used to break intermolecular forces of attraction, increasing intermolecular spaces, and changing the molecular arrangement from solid to liquid
    • The temperature at which a solid converts to a liquid state at atmospheric pressure is called the melting point of the solid

    Factors Affecting Melting Point

    • Effect of pressure: depends on the nature of the solid
      • For solids that expand on melting, increased pressure increases the melting point (e.g., Paraffin wax, silver, gold, and copper)
      • For solids that contract on melting, increased pressure decreases the melting point (e.g., ice, cast iron, brass)

    Latent Heat

    • There are two types of latent heat: latent heat of fusion and latent heat of vaporization

    Latent Heat of Fusion

    • Defined as the amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure without any change in temperature at its melting point
    • Latent heat of fusion of ice is 3.34 x 10^5 J/kg

    Melting Process

    • When a solid is heated, molecules absorb heat energy, increasing kinetic energy and temperature
    • Further heat energy is used to break intermolecular forces of attraction, increasing intermolecular spaces, and changing the molecular arrangement from solid to liquid
    • The temperature at which a solid converts to a liquid state at atmospheric pressure is called the melting point of the solid

    Factors Affecting Melting Point

    • Effect of pressure: depends on the nature of the solid
      • For solids that expand on melting, increased pressure increases the melting point (e.g., Paraffin wax, silver, gold, and copper)
      • For solids that contract on melting, increased pressure decreases the melting point (e.g., ice, cast iron, brass)

    Effect of Impurities on Melting Point

    • Addition of impurities to a solid decreases its melting point, allowing it to melt at a lower temperature.
    • Example: Rose's metal alloy (tin, lead, and bismuth) has a melting point of 94.5°C, lower than the individual melting points of its components: Pb (327°C), Sn (231.9°C), and Bi (271°C).

    Freezing

    • Freezing is the process of converting a liquid to a solid state, opposite to melting.
    • The temperature at which a liquid converts to a solid at atmospheric pressure is called the freezing point.
    • Factors that affect the melting point of a substance also affect its freezing point.

    Freezing Mixtures

    • A mixture of 3 parts ice and 1 part common salt is called a freezing mixture, used to produce a lower temperature (e.g., -21°C).
    • Freezing mixtures are used for preserving food, especially perishables like fish, meats, and frozen foods.

    Unique Properties of Ice

    • Ice is less dense as a solid than as a liquid, unlike most substances that become denser when frozen.
    • Water expands 7.7% in volume when it freezes, due to its molecules forming a latticework of hexagons with empty space.
    • Ice has a density of 0.917 g/cm³, while water has a maximum density of 1.00 g/cm³ at 3.98°C.
    • The expansion of ice is responsible for weathering of paved surfaces, and its unique properties allow it to float on water.

    Survival of Aquatic Animals in Frozen Lakes

    • Pure water has a maximum density at 4°C and a minimum density at 0°C.
    • Ice at 0°C has a lower density than water, causing it to float.
    • Water expands instead of compressing between 0°C and 4°C, remaining in a liquid state.
    • Oxygen is trapped beneath the layer of ice, allowing fish and aquatic animals to survive in frozen lakes.

    Effect of Impurities on Melting Point

    • Addition of impurities to a solid decreases its melting point, allowing it to melt at a lower temperature.
    • Example: Rose's metal alloy (tin, lead, and bismuth) has a melting point of 94.5°C, lower than the individual melting points of its components: Pb (327°C), Sn (231.9°C), and Bi (271°C).

    Freezing

    • Freezing is the process of converting a liquid to a solid state, opposite to melting.
    • The temperature at which a liquid converts to a solid at atmospheric pressure is called the freezing point.
    • Factors that affect the melting point of a substance also affect its freezing point.

    Freezing Mixtures

    • A mixture of 3 parts ice and 1 part common salt is called a freezing mixture, used to produce a lower temperature (e.g., -21°C).
    • Freezing mixtures are used for preserving food, especially perishables like fish, meats, and frozen foods.

    Unique Properties of Ice

    • Ice is less dense as a solid than as a liquid, unlike most substances that become denser when frozen.
    • Water expands 7.7% in volume when it freezes, due to its molecules forming a latticework of hexagons with empty space.
    • Ice has a density of 0.917 g/cm³, while water has a maximum density of 1.00 g/cm³ at 3.98°C.
    • The expansion of ice is responsible for weathering of paved surfaces, and its unique properties allow it to float on water.

    Survival of Aquatic Animals in Frozen Lakes

    • Pure water has a maximum density at 4°C and a minimum density at 0°C.
    • Ice at 0°C has a lower density than water, causing it to float.
    • Water expands instead of compressing between 0°C and 4°C, remaining in a liquid state.
    • Oxygen is trapped beneath the layer of ice, allowing fish and aquatic animals to survive in frozen lakes.

    Boiling and Latent Heat of Vaporization

    • Boiling is the process by which a liquid changes into a gaseous state by absorbing heat energy.
    • Latent heat of vaporization is the quantity of heat in joules required to convert 1 kilogram of a liquid at its boiling point to vapor or gas, without any change in temperature.
    • The latent heat of vaporization of water is 22.5 x 10^5 joules per kilogram (or 225 x 10^5 J/kg).

    Temperature Conversion

    Celsius to Kelvin Scale

    • To convert temperature from Celsius to Kelvin, add 273 to the Celsius temperature.
    • Example: 0°C = 0 + 273 = 273 K, 100°C = 100 + 273 = 373 K.

    Kelvin to Celsius Scale

    • To convert temperature from Kelvin to Celsius, subtract 273 from the Kelvin temperature.
    • Example: 373 K = 373 - 273 = 100°C, 273 K = (273 - 273) = 0°C.

    Kelvin to Fahrenheit Scale

    • To convert temperature from Kelvin to Fahrenheit, use the formula: (9/5)C + 32 = F.

    Conversions

    • Example conversions:
      • 300 K = (300 - 273) = 27°C.
      • 573 K = (573 - 273) = 300°C.
      • 27°C = 27 + 273 = 300 K.
      • 378°C = 378 + 273 = 651 K.
      • 108°F = (108 - 32) × 5/9 = 42.2°C.

    Boiling and Latent Heat of Vaporization

    • Boiling is the process by which a liquid changes into a gaseous state by absorbing heat energy.
    • Latent heat of vaporization is the quantity of heat in joules required to convert 1 kilogram of a liquid at its boiling point to vapor or gas, without any change in temperature.
    • The latent heat of vaporization of water is 22.5 x 10^5 joules per kilogram (or 225 x 10^5 J/kg).

    Temperature Conversion

    Celsius to Kelvin Scale

    • To convert temperature from Celsius to Kelvin, add 273 to the Celsius temperature.
    • Example: 0°C = 0 + 273 = 273 K, 100°C = 100 + 273 = 373 K.

    Kelvin to Celsius Scale

    • To convert temperature from Kelvin to Celsius, subtract 273 from the Kelvin temperature.
    • Example: 373 K = 373 - 273 = 100°C, 273 K = (273 - 273) = 0°C.

    Kelvin to Fahrenheit Scale

    • To convert temperature from Kelvin to Fahrenheit, use the formula: (9/5)C + 32 = F.

    Conversions

    • Example conversions:
      • 300 K = (300 - 273) = 27°C.
      • 573 K = (573 - 273) = 300°C.
      • 27°C = 27 + 273 = 300 K.
      • 378°C = 378 + 273 = 651 K.
      • 108°F = (108 - 32) × 5/9 = 42.2°C.

    Factors Affecting Boiling Point

    • The boiling point of a liquid increases with an increase in external pressure.
    • At higher altitudes, water boils at a lower temperature than 100°C due to lower pressure.
    • In a pressure cooker, the steam generated in a fixed volume increases the pressure beyond normal atmospheric pressure, allowing food to cook faster.

    Effect of Impurities

    • Adding impurities to a liquid raises its boiling point beyond the normal boiling point.
    • For example, when common salt is dissolved in water, the solution boils at a temperature greater than 100°C.

    Cooking Time at Different Altitudes

    • The boiling point of a liquid depends on the pressure acting on it.
    • At sea level, water boils at 373 K, but at higher altitudes, it boils at a lower temperature due to lower pressure.
    • Food takes longer to cook at higher altitudes because water boils at a lower temperature, requiring more time to cook.

    Condensation

    • Condensation occurs when a gas or vapour is cooled, causing the kinetic energy of its particles to decrease.
    • As the temperature is further lowered, the attractive forces pull the particles close together, and the gas or vapour condenses into a liquid.

    Effects of Condensation on Climate

    • The formation of dew, fog, and clouds are examples of condensation.
    • The temperature at which the atmospheric air becomes saturated with water vapour is called the dew point.
    • When the temperature falls below the dew point, water vapour condenses, forming dew, fog, or clouds.

    Sublimation

    • Sublimation is the phenomenon where a substance changes directly from the solid to the gaseous state without undergoing the liquid state.
    • Examples of substances that exhibit sublimation include iodine, naphthalene, solid carbon dioxide (dry ice), and ammonium chloride.

    Factors Affecting Boiling Point

    • The boiling point of a liquid increases with an increase in external pressure.
    • At higher altitudes, water boils at a lower temperature than 100°C due to lower pressure.
    • In a pressure cooker, the steam generated in a fixed volume increases the pressure beyond normal atmospheric pressure, allowing food to cook faster.

    Effect of Impurities

    • Adding impurities to a liquid raises its boiling point beyond the normal boiling point.
    • For example, when common salt is dissolved in water, the solution boils at a temperature greater than 100°C.

    Cooking Time at Different Altitudes

    • The boiling point of a liquid depends on the pressure acting on it.
    • At sea level, water boils at 373 K, but at higher altitudes, it boils at a lower temperature due to lower pressure.
    • Food takes longer to cook at higher altitudes because water boils at a lower temperature, requiring more time to cook.

    Condensation

    • Condensation occurs when a gas or vapour is cooled, causing the kinetic energy of its particles to decrease.
    • As the temperature is further lowered, the attractive forces pull the particles close together, and the gas or vapour condenses into a liquid.

    Effects of Condensation on Climate

    • The formation of dew, fog, and clouds are examples of condensation.
    • The temperature at which the atmospheric air becomes saturated with water vapour is called the dew point.
    • When the temperature falls below the dew point, water vapour condenses, forming dew, fog, or clouds.

    Sublimation

    • Sublimation is the phenomenon where a substance changes directly from the solid to the gaseous state without undergoing the liquid state.
    • Examples of substances that exhibit sublimation include iodine, naphthalene, solid carbon dioxide (dry ice), and ammonium chloride.

    Factors Affecting Boiling Point

    • Boiling point of a liquid increases with an increase in external pressure
    • Water boils at a lower temperature than 100°C at higher altitudes due to lower pressure
    • In a pressure cooker, steam generated in a fixed volume increases pressure beyond normal atmospheric pressure, resulting in faster cooking

    Effect of Impurities

    • Boiling point of a liquid increases when a solid substance is dissolved or added to the liquid
    • For example, when common salt is dissolved in water, the solution boils at a temperature greater than 100°C

    Boiling Point and Altitude

    • Boiling point of a liquid depends on the pressure acting on it
    • Water boils at 373 K at sea level where the pressure is 1 atmosphere
    • On mountains, water boils at a lower temperature due to lower pressure, resulting in longer cooking time

    Condensation

    • Condensation occurs when a gas or vapour is cooled by lowering its temperature
    • As the temperature is further lowered, particles slow down and are pulled together by attractive forces, resulting in condensation
    • Examples of condensation include the formation of dew, fog, and clouds

    Effects of Condensation on Climate

    • Dew forms when the air becomes saturated with water vapour and the temperature falls
    • Fog or mist forms when condensation occurs on floating dust particles
    • Clouds form when condensed water droplets appear in the upper part of the atmosphere

    Sublimation

    • Sublimation is the phenomenon where a substance changes directly from a solid to a gas on heating and back to a solid on cooling
    • Examples of substances that exhibit sublimation include iodine, naphthalene, solid carbon dioxide (dry ice), and ammonium chloride

    Dry Ice

    • Solid carbon dioxide (CO2) is called dry ice because it sublimes, meaning it directly changes into the gaseous state (carbon dioxide gas) without passing through the liquid state.
    • Dry ice does not wet the surface it is kept on due to this unique property.
    • Dry ice is used as a refrigerant under the name Dricold.

    Sublimation

    • Iodine is a substance that can sublime, meaning it changes from a solid to a gas without melting.
    • When heated, iodine crystals directly change into violet-colored vapors.
    • The vapors of iodine get deposited on the upper part of the test tube and appear as grey powder, known as sublimate.
    • Naphthalene balls also sublime, directly changing into vapor state without changing into a liquid.

    Properties of Gases

    • Gases are compressible because the spaces between the gaseous particles decrease when pressure is applied.
    • Gases can be compressed readily due to their compressibility.

    Effect of Pressure and Temperature

    • When the pressure on a liquefied gas is increased and the temperature is lowered, the liquefied gas can change into a solid state.

    Vapors and Gases

    • A substance that under ordinary conditions is a solid or liquid but can exist in a gaseous state under specific conditions is called a vapor.
    • Examples of vapors include water vapor and iodine vapor.
    • A substance that under ordinary circumstances exists as a gas will remain as a gas at room temperature and one atmospheric pressure.
    • Examples of gases include oxygen, nitrogen, and hydrogen.

    Evaporation

    • Evaporation is the process of converting a liquid into a gaseous state.
    • Evaporation can occur without supplying heat energy to the liquid.
    • The surface molecules of a liquid possess higher kinetic energies, allowing them to break away from the forces of attraction and change into a vapor state.
    • Evaporation can occur below a liquid's boiling point.

    Dry Ice

    • Solid carbon dioxide (CO2) is called dry ice because it sublimes, meaning it directly changes into the gaseous state (carbon dioxide gas) without passing through the liquid state.
    • Dry ice does not wet the surface it is kept on due to this unique property.
    • Dry ice is used as a refrigerant under the name Dricold.

    Sublimation

    • Iodine is a substance that can sublime, meaning it changes from a solid to a gas without melting.
    • When heated, iodine crystals directly change into violet-colored vapors.
    • The vapors of iodine get deposited on the upper part of the test tube and appear as grey powder, known as sublimate.
    • Naphthalene balls also sublime, directly changing into vapor state without changing into a liquid.

    Properties of Gases

    • Gases are compressible because the spaces between the gaseous particles decrease when pressure is applied.
    • Gases can be compressed readily due to their compressibility.

    Effect of Pressure and Temperature

    • When the pressure on a liquefied gas is increased and the temperature is lowered, the liquefied gas can change into a solid state.

    Vapors and Gases

    • A substance that under ordinary conditions is a solid or liquid but can exist in a gaseous state under specific conditions is called a vapor.
    • Examples of vapors include water vapor and iodine vapor.
    • A substance that under ordinary circumstances exists as a gas will remain as a gas at room temperature and one atmospheric pressure.
    • Examples of gases include oxygen, nitrogen, and hydrogen.

    Evaporation

    • Evaporation is the process of converting a liquid into a gaseous state.
    • Evaporation can occur without supplying heat energy to the liquid.
    • The surface molecules of a liquid possess higher kinetic energies, allowing them to break away from the forces of attraction and change into a vapor state.
    • Evaporation can occur below a liquid's boiling point.

    Factors Affecting Evaporation

    • Increasing the temperature of a liquid increases the rate of evaporation, as seen in how wet clothes dry faster in summer than in winter.
    • The rate of evaporation increases with an increase in surface area.

    Humidity of Air

    • Humidity of air, which measures the degree of dampness of air, lowers the rate of evaporation.
    • In rainy seasons, clothes take longer to dry due to high humidity.

    Wind Speed

    • The rate of evaporation of a liquid increases with increasing wind speed, as seen in how switching on a ceiling fan helps dry a wet floor faster.

    Pressure

    • Decreasing the pressure around a liquid increases the rate of evaporation, as molecules move from areas of higher to lower pressure.
    • However, if the vapor pressure of the surrounding increases to a specific level, the rate of evaporation slows down.

    Nature of Liquid

    • Different liquids have different rates of evaporation, depending on their interparticle attractive forces.
    • Liquids with weaker interparticle attractive forces, such as acetone, evaporate faster than those with stronger forces, like water.

    Cooling Produced by Evaporation

    • During evaporation, liquid molecules absorb energy from their surroundings and overcome attractive forces, changing into a vapor state.
    • As a result, the surroundings lose energy, becoming cooler.
    • Examples of cooling produced by evaporation include:
      • The cool sensation produced when alcohol is poured on the palm.
      • The cooling effect of cotton clothes in summer.
      • The formation of water droplets on the outer surface of a glass containing ice-cold water.
      • The cooling of water in earthen pots.

    Factors Affecting Evaporation

    • Increasing the temperature of a liquid increases the rate of evaporation, as seen in how wet clothes dry faster in summer than in winter.
    • The rate of evaporation increases with an increase in surface area.

    Humidity of Air

    • Humidity of air, which measures the degree of dampness of air, lowers the rate of evaporation.
    • In rainy seasons, clothes take longer to dry due to high humidity.

    Wind Speed

    • The rate of evaporation of a liquid increases with increasing wind speed, as seen in how switching on a ceiling fan helps dry a wet floor faster.

    Pressure

    • Decreasing the pressure around a liquid increases the rate of evaporation, as molecules move from areas of higher to lower pressure.
    • However, if the vapor pressure of the surrounding increases to a specific level, the rate of evaporation slows down.

    Nature of Liquid

    • Different liquids have different rates of evaporation, depending on their interparticle attractive forces.
    • Liquids with weaker interparticle attractive forces, such as acetone, evaporate faster than those with stronger forces, like water.

    Cooling Produced by Evaporation

    • During evaporation, liquid molecules absorb energy from their surroundings and overcome attractive forces, changing into a vapor state.
    • As a result, the surroundings lose energy, becoming cooler.
    • Examples of cooling produced by evaporation include:
      • The cool sensation produced when alcohol is poured on the palm.
      • The cooling effect of cotton clothes in summer.
      • The formation of water droplets on the outer surface of a glass containing ice-cold water.
      • The cooling of water in earthen pots.

    Factors Affecting Evaporation

    • The rate of evaporation increases with an increase in temperature, as seen in the faster drying of wet clothes in summer compared to winter.

    Surface Area

    • The rate of evaporation increases as the surface area of the liquid increases.

    Humidity

    • Humidity of air measures the degree of dampness of air and lowers the rate of evaporation, making it harder for clothes to dry in rainy seasons.

    Wind Speed

    • The rate of evaporation increases with an increase in wind speed, as seen in the use of ceiling fans to dry wet floors.

    Pressure

    • The rate of evaporation increases with a decrease in pressure around the liquid, as molecules move from areas of higher pressure to lower pressure to equalize the pressure.

    Nature of Liquid

    • Different liquids have different rates of evaporation, with liquids having weaker interparticle attractive forces evaporating faster (e.g., acetone evaporates faster than water).

    Cooling Produced by Evaporation

    • Evaporation absorbs energy from the surroundings, causing a cooling effect, which is utilized in various daily life activities, such as:
      • The cool sensation produced when alcohol is poured on the palm
      • The cooling effect of cotton clothes during summer
      • The formation of water droplets on the outer surface of glasses containing ice-cold water
      • The cooling of water in earthen pots

    Evaporation and Cooling

    • Evaporation causes cooling because only high-energy particles leave the liquid surface, leaving behind particles with low energy, which lowers the average molecular energy and temperature of the remaining liquid.

    Plasma: A State of Matter

    • Plasma is the fourth phase of matter, apart from solids, liquids, and gases.
    • It is formed by heating and ionizing a gas, creating a collection of charged particles that respond strongly to electromagnetic fields.
    • Plasma has unique properties, including electrical conductivity due to free electrical charges.
    • Examples of plasma can be found in nature (flames, interstellar nebulae, aurora borealis, lightning, stars) and artificially (fluorescent lights, neon signs).

    Characteristics of Plasma

    • Plasma is an "ionized gas" composed of electrically charged particles, often described as "super energetic and super excited particles".
    • The state consists of ionized gases, not super excited particles.
    • Plasma glows with a color depending on the nature of the gas, not just the temperature.

    Bose-Einstein Condensate (BEC)

    • A BEC is a gaseous superfluid phase formed by atoms cooled to temperatures near absolute zero.
    • The first BEC was produced in 1995 by Eric Cornell, Ketterle, and Carl Wieman using a gas of rubidium atoms cooled to 170 nanokelvins.
    • BEC is the opposite of plasma, consisting of "super unexcited and super cold atoms".
    • At absolute zero (0 K), molecular motion stops, and atoms clump together, forming a single "super atom" with the same qualities.

    Evaporation and Cooling

    • Evaporation causes cooling because it involves the departure of high-energy particles from the liquid surface, leaving behind particles with low energy.
    • As a result, the average molecular energy of the remaining particles in the liquid state is lowered, leading to a decrease in temperature.

    Plasma

    • Plasma is a fourth phase of matter, distinct from solids, liquids, and gases.
    • It is a collection of charged particles that respond strongly and collectively to electromagnetic fields, taking the form of gas-like clouds or ion beams.
    • Plasma is formed by heating and ionizing a gas, losing its electrons due to heat.
    • It has neither a definite volume nor a definite shape.
    • Free electrical charges in plasma make it electrically conductive.
    • Examples of plasma include flames, interstellar nebulae, aurora borealis, lightning, stars, and fluorescent lights.

    Properties of Plasma

    • Plasma is composed of charged particles, including ions and free electrons.
    • The particles in plasma are electrically charged, making it an "ionized gas".
    • The glow of plasma depends on the nature of the gas, not just the temperature.

    Bose-Einstein Condensate (BEC)

    • A BEC is a gaseous superfluid phase formed by atoms cooled to temperatures near absolute zero.
    • The first BEC was produced in 1995 by Eric Cornell, Ketterle, and Carl Wieman using a gas of rubidium atoms.
    • The BEC is formed at super low temperatures, near 0 K, where all molecular motion stops.
    • Atoms begin to clump together, forming a super atom, where thousands of separate atoms become one entity with the same qualities.

    Matter Around Us

    • Matter refers to elements, compounds, and mixtures combined.

    Pure Substances

    • A pure substance is made up of only one kind of particles (atoms or molecules).
    • A pure substance is uniform or homogenous throughout.
    • Examples of pure substances include water (made up of only one kind of particle called water molecules).
    • Pure substances have a fixed composition and a fixed melting or boiling point.
    • Based on the nature of the constituent particle, pure substances are of two types:
      • Elements: made up of only one kind of atom.
      • Compounds: made up of only one kind of molecule.

    Mixtures

    • A mixture is a material that contains two or more different kinds of particles (atoms or molecules) that do not react chemically but are physically mixed in any proportion.
    • Mixtures are impure substances.
    • Examples of mixtures include a solution of common salt (sodium chloride) in water.
    • Mixtures have a variable composition, i.e., does not have a fixed composition.
    • Mixtures do not have a fixed melting point or fixed boiling point.

    Composite Materials

    • Composite materials combine the properties of two or more constituents to achieve specific properties needed for a particular job.
    • Examples of composite materials include:
      • Steel: used to make rust-free, unbreakable utensils.
      • Bone: a composite material.
      • Wood: consists of cellulose mixed with lignin, which is largely responsible for the strength of the wood.

    Matter Around Us

    • Matter refers to elements, compounds, and mixtures combined.

    Pure Substances

    • A pure substance is made up of only one kind of particles (atoms or molecules).
    • A pure substance is uniform or homogenous throughout.
    • Examples of pure substances include water (made up of only one kind of particle called water molecules).
    • Pure substances have a fixed composition and a fixed melting or boiling point.
    • Based on the nature of the constituent particle, pure substances are of two types:
      • Elements: made up of only one kind of atom.
      • Compounds: made up of only one kind of molecule.

    Mixtures

    • A mixture is a material that contains two or more different kinds of particles (atoms or molecules) that do not react chemically but are physically mixed in any proportion.
    • Mixtures are impure substances.
    • Examples of mixtures include a solution of common salt (sodium chloride) in water.
    • Mixtures have a variable composition, i.e., does not have a fixed composition.
    • Mixtures do not have a fixed melting point or fixed boiling point.

    Composite Materials

    • Composite materials combine the properties of two or more constituents to achieve specific properties needed for a particular job.
    • Examples of composite materials include:
      • Steel: used to make rust-free, unbreakable utensils.
      • Bone: a composite material.
      • Wood: consists of cellulose mixed with lignin, which is largely responsible for the strength of the wood.

    Matter Around Us

    • Matter refers to elements, compounds, and mixtures combined.

    Pure Substances

    • A pure substance is made up of only one kind of particles (atoms or molecules).
    • A pure substance is uniform or homogenous throughout.
    • Examples of pure substances include water (made up of only one kind of particle called water molecules).
    • Pure substances have a fixed composition and a fixed melting or boiling point.
    • Based on the nature of the constituent particle, pure substances are of two types:
      • Elements: made up of only one kind of atom.
      • Compounds: made up of only one kind of molecule.

    Mixtures

    • A mixture is a material that contains two or more different kinds of particles (atoms or molecules) that do not react chemically but are physically mixed in any proportion.
    • Mixtures are impure substances.
    • Examples of mixtures include a solution of common salt (sodium chloride) in water.
    • Mixtures have a variable composition, i.e., does not have a fixed composition.
    • Mixtures do not have a fixed melting point or fixed boiling point.

    Composite Materials

    • Composite materials combine the properties of two or more constituents to achieve specific properties needed for a particular job.
    • Examples of composite materials include:
      • Steel: used to make rust-free, unbreakable utensils.
      • Bone: a composite material.
      • Wood: consists of cellulose mixed with lignin, which is largely responsible for the strength of the wood.

    Definition of Elements

    • Robert Boyle was the first to use the term "element" in 1661.
    • Antoine Lavoisier defined an element as the simplest form of a pure substance that cannot be broken or built up from simpler substances by physical or chemical methods.
    • However, this definition is no longer considered accurate due to the discovery of radioactivity and the synthesis of elements from simpler substances.
    • The modern definition of an element is a pure substance that consists of only one kind of atoms.

    Characteristics of Elements

    • An element is made up of only one kind of atoms, which are identical in all respects (size, mass, composition, etc.).
    • Atoms of different elements differ in size, mass, and composition.
    • There are 118 elements discovered so far, with 90 occurring naturally and 28 synthesized in laboratories.

    States of Elements

    • Majority of the elements are solids at room temperature (e.g., iron, copper, aluminium, silver, gold, sodium, potassium, sulphur, phosphorus, carbon).
    • Only two elements, mercury and bromine, are liquids at room temperature.
    • Gallium and caesium become liquid at a temperature slightly above room temperature (303 K).
    • Eleven elements are gaseous at room temperature (e.g., hydrogen, oxygen, nitrogen, fluorine, chlorine, helium, neon, argon, krypton, xenon, and radon).

    Classification of Elements

    • Elements can be classified into three categories based on physical properties: metals, non-metals, and metalloids.

    Physical Properties of Metals

    • Metals are malleable, meaning they can be hammered or beaten to form thin sheets without breaking.
    • Some metals are more malleable than others (e.g., gold and silver are the most malleable).

    Definition of Elements

    • Robert Boyle was the first to use the term "element" in 1661.
    • Antoine Lavoisier defined an element as the simplest form of a pure substance that cannot be broken or built up from simpler substances by physical or chemical methods.
    • However, this definition is no longer considered accurate due to the discovery of radioactivity and the synthesis of elements from simpler substances.
    • The modern definition of an element is a pure substance that consists of only one kind of atoms.

    Characteristics of Elements

    • An element is made up of only one kind of atoms, which are identical in all respects (size, mass, composition, etc.).
    • Atoms of different elements differ in size, mass, and composition.
    • There are 118 elements discovered so far, with 90 occurring naturally and 28 synthesized in laboratories.

    States of Elements

    • Majority of the elements are solids at room temperature (e.g., iron, copper, aluminium, silver, gold, sodium, potassium, sulphur, phosphorus, carbon).
    • Only two elements, mercury and bromine, are liquids at room temperature.
    • Gallium and caesium become liquid at a temperature slightly above room temperature (303 K).
    • Eleven elements are gaseous at room temperature (e.g., hydrogen, oxygen, nitrogen, fluorine, chlorine, helium, neon, argon, krypton, xenon, and radon).

    Classification of Elements

    • Elements can be classified into three categories based on physical properties: metals, non-metals, and metalloids.

    Physical Properties of Metals

    • Metals are malleable, meaning they can be hammered or beaten to form thin sheets without breaking.
    • Some metals are more malleable than others (e.g., gold and silver are the most malleable).

    Uses of Metals

    • Silver foil is used for decorating sweets.
    • Aluminium foil is used for wrapping medicines, cigarettes, and food items like biscuits and chocolates.
    • Milk bottle caps are also made up of aluminium foil.
    • Sheets of iron, copper, and aluminium are used for making utensils, containers, and bodies of automobiles.

    Physical Properties of Metals

    • Metals are ductile, meaning they can be drawn or stretched into thin wires.
    • Gold and silver are the most ductile metals.
    • Gold is so ductile that 1 gram of it can be drawn to form a wire of about 2 kilometer length.
    • Metals are good conductors of heat, with copper being the best conductor after silver.
    • Lead is the poorest conductor of heat.
    • Metals are good conductors of electricity, with silver being the best conductor.
    • Copper, gold, and aluminium are also good conductors of electricity.
    • Metals like lead and mercury offer very high resistance to the flow of electric current and are poor conductors of electricity.
    • Metals are lustrous due to their shining surface, making them good reflectors.
    • Silver metal is an excellent reflector of light and is used for silvering of mirrors.
    • Metals are generally hard, but some metals like sodium and potassium are soft and can be easily cut with a knife.
    • Metals have high tensile strength, meaning they can hold large weights without breaking.
    • Steel is an alloy of iron and carbon and is very strong, making it suitable for construction of buildings, bridges, and machines.
    • Metals are generally solids at room temperature, except for mercury which is a liquid.
    • Metals generally have high melting and boiling points, except for sodium and potassium which have low melting points.
    • Metals generally have high densities, except for sodium and potassium which have low densities.
    • Metals are sonorous, meaning they make a ringing sound when hit, making them suitable for making musical instruments.

    Physical Properties of Non-Metals

    • Non-metals are not malleable but are brittle, meaning they cannot be hammered or beaten to form thin sheets.
    • Non-metals are not ductile, meaning they cannot be drawn or stretched into wires.
    • Non-metals are bad conductors of heat and electricity, making them insulators.
    • Diamond is an allotropic form of carbon that is a good conductor of heat but bad conductor of electricity.
    • Graphite is another allotropic form of carbon that is a good conductor of heat and electricity and is used for making electrodes of batteries and dry cells.
    • Non-metals are not lustrous but have a dull appearance, except for iodine and graphite which have shining surfaces.
    • Non-metals are generally soft.

    Uses of Metals

    • Silver foil is used for decorating sweets.
    • Aluminium foil is used for wrapping medicines, cigarettes, and food items like biscuits and chocolates.
    • Milk bottle caps are also made up of aluminium foil.
    • Sheets of iron, copper, and aluminium are used for making utensils, containers, and bodies of automobiles.

    Physical Properties of Metals

    • Metals are ductile, meaning they can be drawn or stretched into thin wires.
    • Gold and silver are the most ductile metals.
    • Gold is so ductile that 1 gram of it can be drawn to form a wire of about 2 kilometer length.
    • Metals are good conductors of heat, with copper being the best conductor after silver.
    • Lead is the poorest conductor of heat.
    • Metals are good conductors of electricity, with silver being the best conductor.
    • Copper, gold, and aluminium are also good conductors of electricity.
    • Metals like lead and mercury offer very high resistance to the flow of electric current and are poor conductors of electricity.
    • Metals are lustrous due to their shining surface, making them good reflectors.
    • Silver metal is an excellent reflector of light and is used for silvering of mirrors.
    • Metals are generally hard, but some metals like sodium and potassium are soft and can be easily cut with a knife.
    • Metals have high tensile strength, meaning they can hold large weights without breaking.
    • Steel is an alloy of iron and carbon and is very strong, making it suitable for construction of buildings, bridges, and machines.
    • Metals are generally solids at room temperature, except for mercury which is a liquid.
    • Metals generally have high melting and boiling points, except for sodium and potassium which have low melting points.
    • Metals generally have high densities, except for sodium and potassium which have low densities.
    • Metals are sonorous, meaning they make a ringing sound when hit, making them suitable for making musical instruments.

    Physical Properties of Non-Metals

    • Non-metals are not malleable but are brittle, meaning they cannot be hammered or beaten to form thin sheets.
    • Non-metals are not ductile, meaning they cannot be drawn or stretched into wires.
    • Non-metals are bad conductors of heat and electricity, making them insulators.
    • Diamond is an allotropic form of carbon that is a good conductor of heat but bad conductor of electricity.
    • Graphite is another allotropic form of carbon that is a good conductor of heat and electricity and is used for making electrodes of batteries and dry cells.
    • Non-metals are not lustrous but have a dull appearance, except for iodine and graphite which have shining surfaces.
    • Non-metals are generally soft.

    Non-Metals

    • Non-metals are not strong and have low tensile strength
    • Non-metals can exist in all three states of matter: solid, liquid, and gas
    • Examples of solid non-metals include boron, carbon, sulphur, and phosphorus
    • Bromine is a liquid non-metal, while hydrogen, oxygen, nitrogen, and chlorine are gaseous non-metals
    • Solid non-metals have relatively low melting and boiling points, except for boron, graphite, and diamond
    • Non-metals have low densities and are generally light elements
    • Non-metals exist in different colors, such as sulphur (yellow), phosphorus (white, yellow, or red), and chlorine (yellowish green)
    • Non-metals are not sonorous

    Metalloids

    • Metalloids are elements that have properties in between those of metals and non-metals
    • Examples of metalloids include boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), astatine (At), and polonium (Po)
    • Metalloids show some properties of metals and some properties of non-metals
    • Metalloids are brittle like non-metals and are generally semi-conductors of electricity

    Compounds

    • A compound is a pure substance made up of two or more elements chemically combined in a fixed proportion by mass
    • Examples of compounds include water (H2O), methane (CH4), silica or sand (SiO2), ammonia (NH3), and others
    • A compound is formed because of a chemical change (or reaction) and its properties are entirely different from those of its constituents
    • A chemical compound cannot be formed simply by mixing constituent elements; it is formed only when a chemical reaction takes place between them

    Formation of Compounds

    • Water is not formed when hydrogen and oxygen are simply mixed, but rather when an electric spark is passed through the mixture.
    • The properties of water are different from its constituent elements, e.g., hydrogen is combustible, oxygen supports combustion, but water is neither combustible nor a supporter of combustion.

    Characteristics of Compounds

    • A compound cannot be separated into its constituents by simple physical means, such as filtration, evaporation, distillation, solvent extraction, or using a magnet.
    • A compound has a definite molecular formula and fixed melting point and boiling point.
    • Energy in the form of heat or light is usually evolved or absorbed when a compound is formed.
    • A compound is a homogeneous substance, meaning every part of it looks alike and has the same properties.

    Criteria of Purity of Compounds

    • A solid compound is said to be pure if it has a sharp melting point, i.e., the whole of the solid melts within a range of 0.5°C or 0.5 K.
    • A liquid compound is said to be pure if it has a fixed boiling point, i.e., the whole of the liquid distils at a fixed temperature.
    • Impurities lower or depress the melting points of solid compounds and raise the boiling points of liquid compounds.

    Types of Mixtures

    • Most of the matter around us is not pure but is actually a mixture of two or more pure substances.
    • Examples of mixtures include air, milk, and ocean water.

    Homogeneous Mixtures

    • A homogeneous mixture has a uniform composition throughout.
    • The components of a homogeneous mixture are not visible to the naked eye nor even under a microscope.
    • Examples of homogeneous mixtures include:
      • Solutions of sugar in water or other liquids
      • Mixtures of two or more miscible liquids
      • Alloys, such as brass and steel

    Heterogeneous Mixtures

    • A heterogeneous mixture does not have a uniform composition throughout.
    • The components of a heterogeneous mixture are either visible to the naked eye or under a microscope.
    • There are visible boundaries of separation between the components of a heterogeneous mixture.

    Formation of Compounds

    • Water is not formed when hydrogen and oxygen are simply mixed, but rather when an electric spark is passed through the mixture.
    • The properties of water are different from those of its constituent elements, e.g., hydrogen is combustible, oxygen is a supporter of combustion, and water is neither combustible nor a supporter of combustion.
    • A compound cannot be separated into its constituents by simple physical means, but can be done by chemical means, such as electrolysis.

    Characteristics of Compounds

    • A compound has a definite molecular formula and fixed melting point and boiling point.
    • Energy in the form of heat or light is usually evolved or absorbed when a compound is formed.
    • A compound is a homogeneous substance, meaning every part of it looks alike and has the same properties.

    Criteria of Purity of Compounds

    • A solid compound is said to be pure if it has a sharp melting point, i.e., whole of the solid melts within a range of 0.5°C or 0.5 K.
    • A liquid compound is said to be pure if it has a fixed boiling point, i.e., whole of the liquid distills at a fixed temperature.
    • Impurities lower or depress the melting points of solid compounds, while impurities raise the boiling points of liquid compounds.

    Types of Mixtures

    • Homogeneous mixtures have a uniform composition throughout, and the components are not visible to the naked eye or under a microscope.
    • Examples of homogeneous mixtures include:
      • Solutions of sugar in water
      • Mixtures of two or more miscible liquids
      • Alloys (e.g., brass, steel)
    • Heterogeneous mixtures do not have a uniform composition throughout, and the components are either visible to the naked eye or under a microscope.
    • Heterogeneous mixtures have two or more distinct phases.

    Types of Mixtures

    • A mixture of sugar and sand is a heterogeneous mixture because different parts of the mixture have different sugar-sand compositions.
    • Examples of heterogeneous mixtures include iodized salt, gun powder (sulphur + charcoal + KNO3), and suspensions of solids in liquids (e.g., chalk or sand particles in water).

    Pure Substances

    • A container filled with a pure substance is a balloon filled with helium, which is an element.
    • Air, salt water, and chocolate milk are examples of mixtures or impure substances.

    Homogeneity and Mixtures

    • Compounds are homogeneous, but mixtures can be homogeneous or heterogeneous.
    • Homogeneity alone cannot be used to decide between a mixture and a compound.
    • Homogeneous mixtures, such as solutions of common salt, sugar, copper sulphate, etc. in water, are still regarded as mixtures because:
      • They show the properties of their constituents.
      • The constituents can be separated by physical processes, such as distillation.
      • The composition of the mixture is variable, and different amounts of the substance can be dissolved in the same amount of water.
      • The mixture does not have a definite formula.
      • The mixture does not have a fixed boiling point.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    This quiz introduces the basics of chemistry, covering the concept of matter and its properties. Learn about the changes that occur in materials and why they exist.

    More Like This

    Chemistry Basics Quiz
    5 questions

    Chemistry Basics Quiz

    IrresistibleLeopard9997 avatar
    IrresistibleLeopard9997
    Chemistry Basics Quiz
    5 questions

    Chemistry Basics Quiz

    EventfulPun avatar
    EventfulPun
    Chemistry Basics Quiz
    10 questions

    Chemistry Basics Quiz

    EnrapturedAwe avatar
    EnrapturedAwe
    Chemistry Chapter 1: Matter and Properties
    40 questions

    Chemistry Chapter 1: Matter and Properties

    SignificantAloe avatar
    SignificantAloe
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser