Chapter 13 Review Name ___________________________________

True – False: Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.

____ 1. We can measure the increase in kinetic energy of a substance by measuring how much its temperature has increased.

____ 2. The particles in a substance at 100 K have twice the average kinetic energy of the particles at 50 K.

____ 3. Atmospheric pressure is 760 mm Hg.

____ 4. The particles of a liquid do not have enough kinetic energy to overcome the attractive forces between them and escape.

____ 5. As a liquid evaporates, the particles with the highest kinetic energy escape first.

____ 6. In a liquid in a closed container, there are more particles entering the vapor than condensing.

____ 7. In general, ionic solids have low melting points.

____ 8. The temperature of a mixture of ice and water will continue to rise as heat is applied.

____ 9. Is the following statement true or false? According to the kinetic theory, collisions between particles in a gas are perfectly elastic because kinetic energy is transferred without loss from one particle to another and the total kinetic energy remains constant.

____ 10. All the particles in a substance at a given temperature have the same kinetic energy

____ 11. The kinetic theory states that there are no attractions between the particles of a liquid.

____ 12. Evaporation is a cooling process because the particles in a liquid with the highest kinetic energy tend to escape first, leaving the remaining particles with a lower average kinetic energy and, thus, a lower temperature

____ 13. After a liquid reaches its boiling point, its temperature continues to rise until all the liquid vaporizes.

Questions and Problems Answer the following questions or solve the following problems in the space provided.

14. In terms of particles, explain why are there no minus numbers on the Kelvin scale.

15. Explain why it would be difficult to cook an egg to a hard-boiled stage at the top of a mountain.

16. Two beakers on a laboratory bench each contain a mixture of ice and water. Three ice cubes are added to one beaker and 10 mL of hot water are added to the other beaker. The contents of each beaker remain at their original temperature. Explain.

17. Peanut brittle is a candy that is poured out while hot onto a surface. It is allowed to cool and harden into a sheet, which easily breaks into irregularly shaped pieces. The sugar in peanut brittle solidifies without reforming its crystal lattice. What type of solid is peanut brittle?

18. Which type of solid is likely to have the lowest melting point—an ionic solid or a molecular solid? Explain.

19. The normal boiling point of ethanol is 78.5°C. The normal boiling point of water is 100°C. At 75°C, which liquid, ethanol or water, has the greater vapor pressure? Explain.

15. Explain why evaporation leads to cooling of the liquid.

16. The height of a column of mercury in a barometer is 754.3 mm. What is the atmospheric pressure in atm?

b) In kPa?

17. Circle the letter of each sentence that is true about the assumptions of the kinetic theory concerning gases.

a. A gas is composed of particles with insignificant volume that are relatively far apart from each other.

b. Strong attractive forces exist between particles of a gas.

c. Gases tend to collect near the bottom of a container.

d. The paths of uninterrupted travel of particles in a gas are relatively short because the particles are constantly colliding with each other or with other objects.

18. The temperature 0K, or -273.15°C, is called _____________________ zero. Theoretically, particles of matter at this temperature would have no ________________________.

19. Circle the letter next to each sentence that is true about the particles of a liquid.

a. Most of the particles in a liquid have enough kinetic energy to escape into a gaseous state.

b. Liquids are much denser than gases because intermolecular forces reduce the amount of space between the particles in a liquid.

c. Increasing pressure on a liquid has hardly any effect on its volume.

d. Liquid particles are free to slide past one another.

20. As a liquid evaporates, why do only some of the particles break away from the surface of the liquid?

21. Why does the liquid evaporate faster if the temperature is increased?

22. What causes the chill you may feel after stepping out of a swimming pool on a warm, windy day?

23. Circle the letter next to each sentence that is true about vapor pressure.

a. Vapor pressure arises when particles of a liquid in a closed, partly filled container vaporize and collide with the walls of the container.

b. After a time in a closed, partly filled container, a liquid will evaporate and its vapor will condense at equal rates.

c. When the temperature of a contained liquid increases, its vapor pressure increases.

24. When does a liquid boil?

25. How does the average kinetic energy of the helium atoms in a balloon change as the helium gas is heated from
-100.0°C to 73°C?

39. Liquid A has a vapor pressure of 7.37 kPa at 40°C. Liquid B has a vapor pressure of 18.04 kPa at 40°C. Which liquid would evaporate faster at 40°C? Explain your answer.