Name Date Class THE NATURE OF GASES

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1 13.1 THE NATURE OF GASES Section Review Objectives Describe the assumptions of the kinetic theory as it applies to gases Interpret gas pressure in terms of kinetic theory Define the relationship between Kelvin temperature and average kinetic energy Vocabulary kinetic energy kinetic theory gas pressure Part A Completion vacuum atmospheric pressure barometer pascal (Pa) standard atmosphere (atm) Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. The kinetic theory describes the 1 of particles in matter 1. and the forces of attraction between them. The theory assumes 2. that the volume occupied by a gas is mostly 2, that the 3. particles of gas are relatively 3, move 4 of each other, 4. and are in constant 5 motion. The 6 between 5. particles are perfectly elastic so that the total 7 remains 6. constant. Gas pressure results from the simultaneous collisions 7. of billions of particles with an object. Barometers are used to 8. measure 8 pressure. Standard conditions are defined 9. as a temperature of 9 and a pressure of Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 11. Atmospheric pressure is 760 mm Hg. 12. The SI unit of pressure is the pascal. Chapter 13 States of Matter 317

2 13. Atmospheric pressure increases as you climb a mountain because the density of Earth s atmosphere decreases with altitude. 14. When particles of a substance are heated, some of the energy is absorbed by the particle and stored in the form of potential energy. 15. The Kelvin temperature of a substance is directly proportional to the total kinetic energy of the particles in the substance. 16. At any given temperature, the particles of all substances have the same average kinetic energy. Part C Matching Match each description in Column B to the correct term in Column A. Column A Column B vacuum kinetic energy gas pressure atmospheric pressure barometer a. an instrument used to measure atmospheric pressure b. a space where no particles of matter exist c. the energy an object has because of its motion d. results from the force exerted by a gas per unit surface area of an object e. results from the collisions of atoms and molecules in air with objects Part D Questions and Problems Answer the following in the space provided. 22. A gas is at a pressure of 4.30 atm. What is this pressure in kilopascals? In mm Hg? 23. Describe the motion of particles of a gas according to kinetic theory. 24. What simple evidence demonstrates that gas particles are in constant motion? 318 Core Teaching Resources

3 13.2 THE NATURE OF LIQUIDS Section Review Objectives Identify factors that determine physical properties of a liquid Define evaporation in terms of kinetic energy Describe the equilibrium between a liquid and its vapor Identify the conditions under which boiling occurs Vocabulary vaporization evaporation vapor pressure boiling point normal boiling point Part A Completion Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. Liquids are much 1 than gases. Liquids and solids 1. are known as 2 states of matter. The conversion of a liquid 2. to a gas or vapor is called 3. When a liquid that is not 3. 4 changes to a gas, the process is called evaporation. A 4. liquid evaporates faster when heated; however, evaporation itself 5. is a 5 process. When a partially filled container of liquid is 6. sealed, some of the particles at the 6 of the liquid vaporize. 7. These particles collide with the walls of the container, producing 8. a force called 7. The vapor pressure of a liquid can be 9. determined by a device called a 8. A liquid boils when its equals the external pressure. The normal boiling point of a liquid is the temperature at which the vapor pressure is equal to 10. Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 11. Particles in a liquid don t have enough kinetic energy to overcome the attractive forces between them and vaporize. Chapter 13 States of Matter 319

4 12. When a liquid is in a closed container, there are more particles evaporating than condensing. 13. The change of a substance directly from a solid to a gas or vapor is called condensation. 14. The rates of evaporation and condensation are equal at equilibrium. 15. Heating a liquid will increase the temperature of the liquid. 16. During evaporation in an open container, the temperature of a liquid decreases. Part C Matching Match each description in Column B to the correct term in Column A. Column A Column B vapor pressure condensation normal boiling point liquid intermolecular attractions a. a measure of the pressure exerted by a gas above a liquid b. the forces between molecules c. the boiling point of a liquid at a pressure of kpa d. a fluid with a fixed volume e. the change of a gas or vapor directly to a liquid Part D Questions and Problems Answer the following in the space provided. 22. Describe what happens on a particle level when a liquid is at its boiling point. 23. Liquid A has a vapor pressure of 7.37 kpa at 40 C. Liquid B has a vapor pressure of kpa at 40 C. Which liquid would evaporate faster at 40 C? Explain your answer. 24. Explain why evaporation leads to cooling of the liquid. 320 Core Teaching Resources

5 13.3 THE NATURE OF SOLIDS Section Review Objectives Evaluate how the way particles are organized explains the properties of solids Identify the factors that determine the shape of a crystal Explain how allotropes of an element are different Vocabulary melting point crystal unit cell allotropes amorphous solid glass Part A Completion Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. Solids tend to be dense and difficult to 1. They do not 1. flow or take the shape of their containers, like liquids do, because 2. the particles in solids vibrate around 2 points. When a solid 3. is heated until its particles vibrate so rapidly that they are no longer 4. held in fixed positions, the solid 3. The 4 is the 5. temperature at which a solid changes to a liquid. The melting and 6. 5 of a substance are at the same temperature. In general, 7. ionic solids tend to have relatively 6 melting points, while 8. molecular solids tend to have relatively low melting points. Most 9. solids are 7. The particles are arranged in a pattern known 10. as a crystal 8. The smallest subunit of a crystal lattice is the 9. Some solids lack an ordered internal structure and are called 10 solids. Chapter 13 States of Matter 321

6 Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 11. Glasses do not melt at a definite temperature, but soften gradually. 12. Solid substances can exist in more than one form. 13. Allotropes are two or more different elements that exist in the same state with the same crystal system. 14. When the atoms in a solid have a random arrangement, the solid is a glass. 15. The type of bonding that exists between the atoms in a crystal tends to determine the melting point of the solid. Part C Matching Match each description in Column B to the correct term in Column A. Column A Column B crystal unit cell rhombohedral a. describes a solid in which the particles are randomly arranged b. transparent fusion products of inorganic substances that have cooled to a rigid state without crystallizing c. the smallest group of particles within a crystal that retains the geometric shape of the crystal amorphous glasses solid 22. melting point Part D Questions and Problems Answer the following in the space provided. 24. Explain what happens at the particle level when a solid melts. d. the temperature at which a solid changes to a liquid e. has a regular three-dimensional arrangement of particles f. one of the seven crystal systems. g. dense state of matter that has a fixed shape and is not easily compressed 322 Core Teaching Resources

7 13.4 CHANGES OF STATE Section Review Objectives Identify the conditions necessary for sublimation Describe how equilibrium conditions are represented in a phase diagram Vocabulary sublimation triple point phase diagram Part A Completion Use this completion exercise to check your understanding of the concepts and terms that are introduced in this section. Each blank can be completed with a term, short phrase, or number. The change that occurs when a solid goes directly to the gas 1. or vapor state without first becoming a liquid is This change can occur because solids, like liquids, have a Substances that sublime include iodine and solid 4. 3 (dry ice). 5. A graph that shows the relationship between the states of a 6. substance is called a 4 diagram. On this diagram, a line 7. between two phases shows the conditions at which the phases 8. are in 5. The 6 is the only set of conditions at which solid, liquid, and gas phases coexist. The triple point for water is a temperature of 7 and a pressure of 8. Part B True-False Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT. 9. A phase diagram gives information on changes in mass of solids, liquids, and gases. 10. Water could be made to boil at 105 C by increasing the pressure. Chapter 13 States of Matter 323

8 11. The sublimation point of a substance refers to the temperature and pressure at which the substance exists in all three phases of matter. 12. Below the triple point for water, decreasing the pressure will not change water vapor to ice. 13. Water has more than one triple point. 14. At kpa, the normal boiling point and melting point of water are the same. Part C Matching Match each description in Column B to the correct term in Column A. Column A Column B melting freeze drying phase diagram C, 0.61 kpa sublimation a. the change of a solid to a vapor without passing through the liquid state b. the change of a solid to the liquid state c. a method of removing water from food, using sublimation d. graph that shows the relationship among the states of a substance e. defines the triple point for water C at kpa Part D Questions and Problems f. normal boiling point for water Answer the following in the space provided. 21. Explain how some solids can vaporize and then condense back to a solid without passing through the liquid state. What is the process called? 22. When the physical state of a substance changes during a phase change, what happens to the temperature of the system? 324 Core Teaching Resources