Matter In Our Surroundings PDF

Matter in Our Surroundings  Topics to be Covered Introduction to Matter Physical Nature of Matter Characteristics of Particles of Matter States of Matter Can Matter Change its State? Evaporation  Introduction to Matter “Anything that has mass and occupies space is called matter.”...

Matter in Our Surroundings  Topics to be Covered Introduction to Matter Physical Nature of Matter Characteristics of Particles of Matter States of Matter Can Matter Change its State? Evaporation  Introduction to Matter “Anything that has mass and occupies space is called matter.” e.g. table, chair, air, water, honey, etc. MASS + SPACE “MATTER” Classification of matter: MATTER PHYSICAL PROPERTIES CHEMICAL PROPERTIES  Physical Nature of Matter MATTER IS MADE UP OF PARTICLES: Matter is made up of tiny particles, these tiny particles are called atoms. These particles are so small that we cannot see them with our eyes or a regular microscope. HOW SMALL ARE THESE PARTICLES OF MATTER? Particles of matter are so small that they cannot be seen with the naked eye. They can be observed using powerful microscopes. The particles of matter are very small – they are small beyond our imagination!!!!  ACTIVITY 1.2 “Experiment ka funda” Dissolve 2–3 crystals of potassium permanganate in 100 mL of water. Take 10 mL of this solution and add it to 90 mL of clear water. Repeat this 5 to 8 times. Observation: The water remains colored even after many dilutions. Conclusion: Just a few crystals can color a lot of water, showing there are millions of tiny particles in each crystal. “The particles of matter are incredibly small!”  Characteristics of Particles of Matter Particles of Matter Have Spaces Between Them The extent of these spaces varies in different states of matter (solids have the least space, gases have the most). Example: When sugar is dissolved in water, we will get a clear solution where the sugar takes up the small interspaces in between the water, the sugar will dissolve until all the spaces are occupied by them. no change in level of water  Characteristics of Particles of Matter Particles of Matter are in Constant Motion Particles of matter are always moving. The movement is least in solids (vibrating in place), more in liquids (sliding past each other), and most in gases (moving freely at high speeds). Example: The smell of perfume spreads in a room because the perfume particles diffuse through the air particles, smell of food being cooked. The burning of incense stick produces gases or vapours having pleasant smell. The particles of gases produced by the burning of incense stick move rapidly in all directions, mix with the moving particles of air in the room and reach every part of the room quickly along with the air.  es am pl Diffusion ex The mixing of a substance with another substance due to the motion or movement of its particles is called diffusion. Diffusion can take place in gases, liquids, and solids, though it is fastest in gases and slowest in solids. Energy possesed due to the motion of particles is called Kinetic Energy. Higher temperatures increase the kinetic energy of particles, causing them to move faster and thus increasing the rate of diffusion. Heating makes diffusion faster because particles move more quickly.  Characteristics of Particles of Matter Particles of Matter Attract Each Other Take an iron nail, a stick of chalk, and a pen. Try to break each one of these. Which one of these is easy to break? In every substance, there is an inter-particle force of attraction acting between its particles. To break something we need to overcome this force. The strength of the force differs from one substance to another. The inter-particle force of attraction and the kinetic energy of the particles primarily determine the physical state of any matter. We can move our hand through the air effortlessly because the particles in the air have a negligible force of attraction. Similarly, moving our hand through water in a bucket is fairly easy because the attraction between water particles is also weak. However, trying to move our hand through a solid object like a wooden plank is difficult and would likely hurt us because the particles in the wood are held together by very strong forces. Less Force of High Force of attraction attraction  In Short Kaam ki Baat The important characteristics of particles of matter are the following: The particles of matter are very, very small. The particles of matter have space between them. The particles of matter are constantly moving. The particles of matter attract each other.  States of Matter Solids Liquids Gases Properties of Solids, Liquids and Gases :  Property Solids Liquids Gases More space than solids, less Space Between Particles Very little space Particles are far apart than gases Strong, but not strong enough to Force of Attraction Very strong Negligible hold position Can slip and slide over each Particle Arrangement Closely packed, orderly Very disorderly other, disorderly Shape Fixed shape Takes the shape of the container No definite shape No definite volume, fills Volume Fixed volume Fixed volume container Almost negligible Compressibility Cannot be compressed Can be compressed easily compressibility Kinetic Energy Very low Higher than solids Maximum kinetic energy Movement of Particles Vibrate in fixed positions Can move past one another Move freely in all directions Example Ice, iron Water, oil Air, helium a, b and c show the magnified schematic pictures of the three states of matter. The motion of the particles can be seen and compared in the three states of matter. GASES: The particles are much farther apart from one another as compared to solids and liquids.They have a very disorderly arrangement of particles compared to the solids and liquids. The force of attraction between the particles is negligible, hence particles of a gas move freely in all the directions. Gases thus can mix or diffuse into other gases. The particles of a gas have maximum kinetic energy. They move with high speed in all directions and can exert pressure on the walls of its container. Gases neither have a definite shape nor a definite volume.They fill up the container completely. Gases can be compressed easily. Example: the LPG cylinders used at home and the CNG cylinders used in vehicles. Soch kr bataao? (a) What about a rubber band, can it change its shape on stretching? Is it a solid? (b) What about sugar and salt? When kept in different jars these take the shape of the jar. Are they solid? (c) What about a sponge? It is a solid yet we are able to compress it. Why?  PLASMA Plasma is often referred to as the fourth state of matter. It is a high- energy, ionized state of matter where atoms have been stripped of their electrons, resulting in a mixture of free electrons and ions. Natural Plasmas: The sun and other stars are made up of plasma. The high temperatures in stars cause atoms to ionize, creating plasma. Man-Made Plasmas: Neon signs and other types of gas discharge tubes use plasma to produce light. When an electric current passes through the gas, it ionizes the gas particles, creating plasma that emits light.  Bose-Einstein Condensate Indian physicist Satyendra Nath Bose made a study regarding the fifth state of matter. Based on his study, Albert Einstein predicted a fifth state of matter called the Bose-Einstein Condensate. The Bose-Einstein Condensate or BEC is formed by cooling a gas of extremely low density to super low temperatures. Satyendra Nath Bose Albert Einstein  Some Important SI Units The SI unit of mass is kilogram (kg). The SI unit of volume is cubic metre (m 3 ) The common unit of measuring volume is litre (L) such that 3 3 1L = 1 dm , 1L = 1000 mL, 1 mL = 1 cm The SI unit of temperature is Kelvin (K). Other than this, temperature can be expressed in degree C and Fahrenheit. Important to Remember: 0 degree C = 273K 25 degree C = 298K 100 degree C = 373K Round of 273.15 to 273 Q. Change the temperature in Celsius scale temperature (a) 293 K (b) 470 K  Can Matter Change its State? Yes, matter can change its state under different conditions of temperature and pressure.  Effect of Temperature Increasing Temperature of Solids: Increases kinetic energy, causing particles to vibrate faster. Heat overcomes attraction forces, making particles move freely. Leads to melting when a solid converts to a liquid. Similarly, liquids also undergo a phase change to form gases. Melting Point: The minimum temperature at which a solid becomes a liquid. Indicates the strength of attraction between particles. Ice melts at 273.15 K (0°C). Fusion: The process of solid changing to liquid. During melting, temperature remains constant until all solid melts. Heat energy used to overcome attraction forces is called latent heat. Latent Heat of Fusion: Heat needed to convert 1 kg of solid to liquid at melting point. The heat is being absorbed by the particles of ice to overcome the force of attraction between them and get converted to water. Boiling: Heating water increases particle movement. Boiling Point: The temperature at which a liquid changes to gas at atmospheric pressure (373 K for water).  Boiling is a bulk phenomenon. Particles from the bulk of the liquid gain energy to change into the gaseous state. For example, boiling point of water is 100° C. (or 100° C = 273 + 100 = 373 K) Latent Heat of Vaporization: Heat needed to convert 1 kg of liquid to gas at boiling point. The heat is being absorbed by the particles of water to overcome the force of attraction between them and get converted to steam. Sublimation: Solid changes directly to gas without becoming liquid. Example: Ammonium chloride, iodine, camphor, naphthalene, dry ice. Deposition: Gas changes directly to solid without becoming liquid. Q. When a Solid melts its temperature remains the same, so where does the heat energy go? Answer: This heat gets used up in changing the state by overcoming the forces of attraction between the aprticles.  Effect of Pressure 1) Physical state of matter can also be changed by increasing or decreasing the pressure. 2) The gases can be changed into liquids by increasing the pressure. 3) Solids can be changed into gases by decreasing the pressure. 4) Gases can be liquefied by applying Pressure and Lowering Temperature. Pressure and temperature together determine whether a substance is solid, liquid, or gas. What is dry ice? why it is stored under high pressure? Solid carbon dioxide, also known as dry ice, is stored under high pressure because it directly converts to carbon dioxide gas when the pressure is decreased. At room temperature, carbon dioxide is a gas, so it requires very low temperatures and high pressure to convert it into a solid. When carbon dioxide gas is compressed under high pressure, the particles get closer together and eventually turn into dry ice.  EVAPORATION The phenomenon of change of liquid into vapours at any temperature below its boiling point is called evaporation. For example, the gradual drying of damp clothes is caused by the evaporation of water to water vapour. During evaporation, liquid particles gain energy from their surroundings in order to overcome the force of attraction between them. As a result, heat energy is lost in the surrounding environment.  Factors Affecting Evaporation Temperature: The rate of evaporation increases with an increase in temperature. Surface area: The rate of evaporation increases with an increase in surface area. Humidity: The rate of evaporation decreases with an increase in humidity. Wind speed: The rate of evaporation increases with an increase in wind speed.  Cooling due to Evaporation During evaporation, the particles of a liquid absorb energy from the surroundings to overcome the inter-particle forces of attraction and undergo phase change. The absorption of heat from the surrounding makes the surroundings cool. To keep our bodies cool, we sweat a lot. Evaporation is what transpiration ultimately is. Our body’s water evaporates, using energy in the process and lowering our body temperature as a result. To keep water cool, it is kept in earthenware containers. Similar to the pores in cotton fabric, the pores in the earthen pot’s surface area allow for more evaporation. Q. Why should we wear cotton clothes in summer? During summer, we sweat more to cool down. Evaporation of sweat absorbs heat from our body, making us feel cool. Cotton clothes absorb sweat and expose it to the air, aiding evaporation and keeping us cooler. Q. Why do we see water droplets on the outer surface of a glass containing ice-cold water? Water droplets form on the outer surface of a glass with ice-cold water because water vapor in the air condenses on the cold surface, turning into liquid. This process is called condensation. Evaporation V/s Boiling  TOP 5 Questions 1. The boiling point of alcohol is 78°C. What is the temperature in kelvin scale? (a) 373K (b) 351K (c) 375K (d) 78K  TOP 5 Questions 2. Which of the following phenomena always results in the cooling effect? a) Condensation b) Evaporation c) Sublimation d) None of these  TOP 5 Questions 3. When a crystal of potassium permanganate is placed at the bottom of water in a beaker, the water in the whole beaker turns purple on its own, even without stirring. This is an example of : (A) distribution (B) intrusion (C) diffusion (D) effusion  TOP 5 Questions 4. Which of the following conditions is most favourable for converting gas into liquid? (a) High pressure, low temperature (b) Low pressure, low temperature (c) Low pressure, high temperature (d) High pressure, high temperature  TOP 5 Questions 5. Which of the following phenomena would increase on rising temperature? (a) Diffusion, evaporation, compression of gases (b) Evaporation, compression of gases, solubility (c) Evaporation, diffusion, expansion of gases (d) Evaporation, solubility, diffusion, compression of gases