CHAPTER 1 - STATES OF MATTER.pdf

STATES OF MATTER CHAPTER 1 PAGES 2 - 13 CHEMISTRY FOR CSEC, 2ND EDITION CHEMISTRY The study of the structure and behavior of matter. Everything around us is made of matter!  A1.1 THE PARTICULATE NATURE OF MATTER 1...

STATES OF MATTER CHAPTER 1 PAGES 2 - 13 CHEMISTRY FOR CSEC, 2ND EDITION CHEMISTRY The study of the structure and behavior of matter. Everything around us is made of matter!  A1.1 THE PARTICULATE NATURE OF MATTER 1 2 3 4 5 Give the Give the four Explain why Identify the Explain the definition of main ideas of scientists find three main relationship matter the particulate the particulate states of matter between theory of matter theory of matter temperature useful and the motion of particles  GIVE THE DEFINITION OF MATTER Matter is anything that What is matter? has mass and occupies space. WHAT IS THE PARTICULATE THEORY OF MATTER? The particulate theory of matter states that all matter is made up of particles.  The particulate theory of matter has four main ideas: GIVE THE All matter is made of particles FOUR MAIN IDEAS OF THE The particles are in constant, random motion PARTICULATE THEORY OF There are spaces between the MATTER particles There are forces of attraction between the particles  EXPLAIN WHY SCIENTISTS FIND THE PARTICULATE THEORY OF MATTER USEFUL The particulate theory of matter is very useful because it helps us to explain both the physical properties of matter and the differences between the three states of matter. The particulate theory of matter can be used to explain many physical phenomena that we observe in our everyday lives. Example: The difference in density of solids, liquids, and gases, e.g., why pebbles sink, and bubbles rise in water. What are some other examples? IDENTIFY THE THREE MAIN STATES OF MATTER The three main states of matter are: Solids Liquids Gases The difference between these states lies in the energy and arrangement of the particles.  EXPLAIN THE RELATIONSHIP BETWEEN TEMPERATURE AND THE MOTION OF PARTICLES The energy of the particles is This change in state occurs directly related to the because increasing the temperature of the particles temperature of a substance and matter can change increases the kinetic energy from one physical state to of the particles in the another by changing its substance. temperature. Changing state by changing temperature is a physical The greater the kinetic change. A physical change energy the particles possess, occurs when the form of the the faster they move. substance is changed without changing its chemical composition. HOMEWORK SUMMARY QUESTIONS 1 – 5, PAGE 3  A1.2 EVIDENCE FOR THE PARTICULATE THEORY OF MATTER Explain Explain Describe Explain Explain Explain the Describe Explain the uses evidence which processes of experiments of salt and sugar supports the diffusion and which to control particulate osmosis demonstrate garden pests theory of matter diffusion and and preserve osmosis food items  DIFFUSION Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration until they are evenly distributed. Diffusion occurs because particles of matter are in constant motion and will move from a region of higher concentration to one of lower concentration.  EXPERIMENT: INVESTIGATING THE PARTICULATE THEORY OF MATTER 01 02 03 04 05 Place straw Drop crystal of Carefully remove Observe how the What conclusion vertically in the potassium straw. purple color can be drawn beaker of water manganite(VII) spreads. about: until it touches into the straw The spaces between the the bottom of the without moving water particles The movement of the beaker. the straw. potassium manganite(VII) particles EXPERIMENT: POTASSIUM MANGANATE(VII) DIFFUSION  EXPLANATION: POTASSIUM MANGANATE(VII) DIFFUSION The potassium manganate(VII) crystal and the water used in the experiment are both composed of minute particles. Particles of crystals are packed closely together and those in water have very small spaces between them. When the crystal is in water, the minute crystal particles slowly separate from each other and diffuse into the spaces between the water particles. This continues until all the particles have separated from the crystal and have diffused between the water particles. The crystal gradually dissolves, and an aqueous solution is formed. EXPERIMENT: INVESTIGATING DIFFUSION IN GASES Place a glass tube at least 1m in length between two retort stands. Soak separate pieces of cotton wool in concentrated ammonia solution and concentrated hydrochloric acid and place them simultaneously at each end of the glass tube. Seal the ends of the glass tube with rubber stoppers. Observe any changes.  EXPLANATION: INVESTIGATING DIFFUSION IN GASES The ammonia gives off ammonia gas and hydrochloric acid gives off a gas called hydrogen chloride gas. Ammonia and hydrogen chloride particles diffuse through the air in the glass tube towards each other. When the particles meet, they collide and react to form a white solid known as ammonium chloride. The ammonia chloride forms a ring inside the glass tube. The ammonium chloride forms closer to the cotton wool soaked in hydrochloric acid because the ammonia particles are lighter than the hydrogen chloride particles. Therefore, ammonia particles move much faster through the air than hydrogen chloride particles.  The experiment provides the following evidence for the particulate theory of matter: Particles are able to move – the ammonia and hydrogen chloride EXPLANATION: particles must have moved INVESTIGATING towards each other to form the DIFFUSION IN white ring. GASES There are spaces between particles – there must have been spaces between the air, ammonia, and hydrogen chloride particles to allow them to move between each other. OSMOSIS Osmosis is the movement of water molecules from a region with a lot of water molecules, e.g. a dilute solution or pure water, to a region with fewer water molecules, e.g., a concentrated solution, through a differentially permeable membrane.  Osmosis is a special case of diffusion, which involves the movement of water molecules through a differentially permeable membrane. A differentially permeable membrane allows some substances to pass through but not others. This membrane may also be called a semi- permeable membrane or selectively permeable membrane. It contains minute pores. Water molecules are OSMOSIS able to pass through these pores. However, the particles of many other substances are unable to pass through. Two solutions with different concentrations which are separated by a differentially permeable membrane allow water molecules to diffuse through the pores in the membrane from the more dilute solution to the more concentrated solution. The volume of the dilute solution decreases and the volume of the more concentrated solution increases. OSMOSIS: WHAT IS HAPPENING IN THIS DIAGRAM?  EXPERIMENT: INVESTIGATING OSMOSIS IN POTATO 1 2 3 4 5 Cut a potato Measure and Place three tubes into Allow the tubes Measure and a beaker of distilled into six tubes of record the water and place the to remain in the record the equal length. length of each other three tubes into solutions for length of each the beaker tube. containing the one hour. tube. concentrated sucrose solution. EXPERIMENT: INVESTIGATING OSMOSIS IN POTATO  EXPLANATION: INVESTIGATING OSMOSIS IN POTATO During the experiment, the cell membranes of the potato cells act as differentially permeable membranes. Water can pass through the cell membranes, either into or out of the cells: Distilled water has a higher water content (lower sucrose concentration) than the potato cells. Water moves into the cells by osmosis resulting in the potato tubes becoming longer and more rigid. The potato cells have a higher water content than the concentrated sucrose solution. Water moves out of the cells by osmosis resulting in the potato tubes becoming shorter and softer. OSMOSIS: WHAT IS HAPPENING IN THIS DIAGRAM? WRITE YOUR EXPLANATION IN YOUR NOTEBOOK. OSMOSIS: WHAT IS HAPPENING IN THIS DIAGRAM? WRITE YOUR EXPLANATION IN YOUR NOTEBOOK. THE DIFFERENCES BETWEEN DIFFUSION AND OSMOSIS  PRACTICAL USES OF OSMOSIS Controlling garden pests Slugs and snails are serious garden pests. The skin of these pests is a lot more permeable than the skin of most animals. They need to keep themselves moist to prevent water from evaporating from their bodies causing them to dehydrate and die. We can control slugs and snails in our gardens using sodium chloride (table salt). Sodium chloride is deliquescent, which means it absorbs water readily and dissolves. When sodium chloride is sprinkled on slugs and snails, it absorbs some of the moisture surrounding their bodies and dissolves forming a concentrated solution. This causes water inside their bodies to move out and into the solution by osmosis. If the slugs and snails lose more water than their bodies can tolerate, they die from dehydration.  PRACTICAL USES OF OSMOSIS Preserving food items Sodium chloride and sugar are used to preserve food items, e.g. meat, fish, fruits and vegetables. Both salt and sugar work in the same way to preserve foods: They withdraw water from the cells of the food items by osmosis. This makes the water unavailable for the chemical reactions in cells which cause decay. Without these reactions occurring, the food items do not decay. They also withdraw water from the microorganisms that bring about decay, e.g. bacteria and fungi. This prevents these organisms from growing and causing food items to decay. PRESERVING FOOD ITEMS: BEFORE ADDING SALT AND BEFORE OSMOSIS OCCURS HOMEWORK SUMMARY QUESTIONS 1 – 5, PAGE 9  Explain the difference between the three states of Explain matter in terms of energy and arrangement of particles, and forces of attraction between particles Account for the physical properties of the three states Account of matter in terms of energy and arrangement of particles, and forces of attraction between particles A1.3 THE THREE Explain Explain the changes of states in terms of energy and arrangement of particles STATES OF MATTER Understand Understand melting, evaporation, boiling, condensation, freezing and sublimation Understand and Understand and interpret heating and cooling curve interpret  The three states of matter have noticeable differences in their physical properties. Physical properties are characteristics that can be observed or measured without changing the THE THREE chemical composition of a substance. STATES OF Shape, volume, density, compressibility, MATTER solubility, melting point and boiling point are all examples of physical properties. The different physical properties of the three states of matter can be explained by the particulate theory of matter. The properties of the three states of matter  CHANGING STATE Matter can be changed from one state to another by heating or cooling. A change of state is, therefore, caused by a change in temperature and consequently a change in the kinetic energy of the particles. For example, in order to change water into ice we need to remove heat. Changing the state of a substance without changing its chemical composition is a physical change. A summary of all state transitions is provided for you. CHANGING STATE  PROCESSES THAT CAUSE CHANGES IN STATE Melting – when a solid is heated, the particles gain kinetic energy to overcome the forces of attraction and move more freely and further apart forming a liquid. The point at which this occurs is a constant temperature called the melting point. Evaporation – when a liquid is heated, particles gain enough kinetic energy and move faster. Some particles near the surface gain enough kinetic energy to overcome the forces of attraction between them and can leave the liquid and become a vapor. Evaporation leads to cooling. Boiling – when a liquid is heated, the particles within and at the surface of the liquid gain enough energy to be converted to a gas. The point at which this occurs is a constant temperature called the boiling point. Condensation – when the temperature of a gas is lowered, the particles lose kinetic energy and begin to move more slowly. This results in the formation of a liquid as the forces of attraction between the particles become stronger. Freezing – when the temperature of a liquid is lowered, the particles lose kinetic energy and begin to move slowly. Forces of attraction between the particles become stronger and the particles form a solid. The point at which this occurs is a constant temperature called the freezing point. Sublimation – forces of attraction between solid particles are weak and the addition of a small amount of heat causes a solid to change directly to a gas. If the gas is cooled, the reverse process called deposition occurs. E.g., iodine, carbon dioxide, naphthalene.  What is one similarity between evaporation and boiling? SIMILARITIES AND DIFFERENCES What are the two differences between evaporation and boiling?  HEATING AND COOLING CURVES If the temperature of a pure solid is measured at intervals as it is heated and changes state to a liquid and then to a gas, and the temperature is plotted on a graph against time, a heating curve is obtained. If the temperature of a gas is measured at intervals as it is cooled and changes state to a liquid and then to a solid, and the temperature is plotted on a graph against time, a cooling curve is obtained. In both curves there are two horizontal points where the temperature remains constant. At these horizontal points, there is a change of state. During this change of state, both states of matter are present before one state is converted into the other. The following curves will provide more context. HEATING CURVE OF WATER Cooling curves have two horizontal sections. The first is where melting occurs, and the temperature remains constant as a solid is changed to a liquid. The second change of state is where boiling occurs, and the temperature remains constant at the boiling point until all the substance has changed from a liquid to a gas. COOLING CURVE OF WATER Cooling curves have two horizontal sections. The first is where the state changes from gas to liquid. The second is where it changes from liquid to solid. The temperature remains constant during these changes of states and both states exist. HOMEWORK SUMMARY QUESTIONS 1 – 4, PAGE 13 THE END States of Matter