1. Pg 48 20 degrees Celsius = 68 degrees Fahrenheit.

2. 1.8 minutes ; 100 o C It takes more energy to boil the water because you have to heat it longer.

3. Pg 49

4. The particles in ice have a fixed arrangement. The particles in liquid water are free to move.

5. Pg 50

6. Liquids have no definite shape, so a liquid metal can be poured into a mold. After it solidifies, it has a definite shape and can be removed and keep its shape. The particles in a certain amount of liquid copper have more energy that the molecules in the same amount of liquid water because the copper is at a higher temperature.

7. melting. During freezing, the particles take on fixed positions. During melting, the particles break free from those positions and move freely. are vibrating so fast that they break free from their fixed positions.

8. Pg 51

9. In both types, a liquid changes into a gas. Evaporation occurs only on the liquids surface, while boiling occurs both on and below the surface.

10. Water vaporizes from the flask on the right first. Water that is boiled vaporizes faster than water that evaporates. Evaporation Boiling

11. Pg 52 Condensation condenses.

12. Warm water vapor in the air condenses into liquid droplets when it touches the cool surface of the mirror.

13. vaporization. Its thermal energy decreases. The clouds are condensed water vapor. When the droplets get heavy enough, they fall to the ground as rain. gain enough energy to move independently.

14. Pg 53

15. When the dry ice becomes a gas, it cools water vapor in the nearby air. The water vapor condenses into a liquid, forming fog.

16. Pg 54 The water molecules slow down and take on fixed positions.

17. The water molecules speed up and break free from their fixed positions.

18. Pg 55 The water molecules speed up and spread apart, filling all the available space.

19. The water molecules slow down and come closer together. They are still free to move around one another.

20. Solid carbon dioxide. Nothing would be left in the bowl.

21. A substance changes states because it gains or loses thermal energy. skip the liquid state and go directly to the gas state.