1. in Order for an Object to Have Kinetic Energy, It Must Be Moving

Chapter 5 Review

1. In order for an object to have kinetic energy, it must be moving.

2. Temperature is directly related to the average kinetic energy of the particles of a substance.

3. You can decide whether a substance is a solid, liquid or gas by: A solid has a fixed shape. Liquids take the shape of the container and form a surface in the container. Gases take the shape of the container and fill the container.

4. Answers will vary. Refer to the sketch on page 170 #4.

5. An increase in the temperature of an object affects its volume by: Substances expand when the temperature increases. Gases expand the most upon heating.

6. The particle theory of matter explains the ability of a liquid to flow by; The particles in a liquid have enough kinetic energy to break away from adjacent particles but are then attracted to other particles. This 'changing partners' allows the liquid to flow.

7. Name the following changes of state:

a) From a liquid to a solid - Freezing

b) From a solid to a gas - Sublimation

c) From a gas to a liquid – Condensation

8. The particle theory of matter explains evaporation by; When the temperature of a liquid is raised high enough, that is, the particles have enough kinetic energy, they can break away from all attractive forces with all other particles. They become completely free of other particles and are in the gaseous state.

9. What you can say about the forces among the particles of a pure substance if the melting temperature is -40oC is that the attractive forces between particles are weak. The reason is that the particles of a substance have a very low average kinetic energy at -40oC but can still break away from adjacent particles.

10. What is happening to the temperature of a pure substance while it is melting is; the temperature is not changing.

11. Refer to the model on the bottom of page 170.

a) The figures are models of solids, liquids and gases.

b) Each part of the figure models the concept by;

In the figure on the left, particles are touching and holding on to each other and are closely packed - SOLID

In the central figure, particles are holding on to some particles but reaching for others - LIQUID

In the figure on the right, the particles are not touching and appear to be bouncing around – GAS

c) The changes that could be made to this model to make it better are; It might be better if it was more obvious that the particles in the solid were holding tightly to each other. Also, it might be better if each diagram had the same number of particles.

12. Lego blocks can be used to model the particle theory of matter by; Lego blocks can be attached to each other in a wide variety of ways to make very complex structures. They have raised circles and posts that can snap together creating attractive forces between the blocks.

13. If two golf balls are flying through the air, you can tell which one has more kinetic energy by; the golf ball with the greatest speed has the most kinetic energy.

14. Imagine you fall of a bicycle and your arm rubs against the ground. The injury is sometimes called a 'burn.' This could be a suitable description because when one substance rubs against another, the friction causes the particles on the surface to gain kinetic energy, thus raising the temperature. Since the temperature goes up, rubbing can be called a 'burn.'

15. A classmate says that if something takes the shape of the container. it must be a liquid. It could also be a gas because a gas will take the shape of the container.

16. Mercury is the only metal that is liquid at room temperature. All other metals are solids at room temperature. What this tells you about the interactions among the particles of mercury when compared with the particles of other metals is; the attractive forces between particles of mercury must be weaker than the attractive forces between the particles of any other metal.

17. Imagine that you filled a glass to the very top with water directly from the refrigerator. You put it on the table and then answer the telephone. After a long conversation, you discover that there is water all around the glass on the table. What happened was; the water in the glass must have been cold. As the water warmed, it expanded and spilled out of the glass or the gaseous air cooled and formed a liquid around the glass.

18. Two drinking glasses are stuck together, one inside the other. A recommendation for a way to remove the outer glass without breaking either glass could be; heat the outer glass by running hot water over it. The glass will probably expand just enough to slip off of the inner glass.

19. On a winter day, the wind blows briskly all day. At the end of the day, you notice that there is much less snow on your driveway than there was in the morning. However, you did not see any moisture on the pavement all day. What happened to the snow was the wind probably speeded up the sublimation of the snow into water vapor. or A lot of the snow may have blown away.

20. If you wanted to heat a substance to 450oC, you would use an aluminum container because tin melts at 232oC and aluminum melts at 660oC. At 450oC, tin would be a liquid, but the aluminum would still be a solid.

21. Imagine that you put some eggs in a pot of water on the stove and turn it on to boil the eggs. Then, you go to your room to do homework. You were working so hard that you forgot that you had put the eggs on to boil. While you were doing homework, all the water boiled away and the eggs were badly burned. Eggs do not burn when they are in boiling water, but they do burn after the water boils away is because; While water is boiling in the pot, it stays at 100oC. Since it is touching the bottom of the pot, the water removes heat from the pot, preventing it from getting hotter than 100oC. After the water in the pot boils away, the pot continues absorbing heat from the burner and gets much hotter and burns the eggs.