1. Chapter 23: Change of Phase Review and Study Guide

2. What is the phase change during evaporation? Liquid to a gas

3. Where in a liquid does evaporation occur? Evaporation occurs at the surface

4. Is energy absorbed or released during evaporation? Energy is absorbed

5. Why do you feel cold when you get out of the shower with water on your body? Because the water is evaporating. For this to occur, the water is absorbing energy from your body.

6. Why do dogs pant? To cool themselves through evaporation on their tongue, in their mouth and in their throat.

7. What phase change occurs during condensation? Gas changes to a liquid

8. Is energy absorbed or released during condensation? Energy is released, warming the surroundings

9. Why do water droplets form on a cold glass on a warm day? Because the gas particles give up their energy to the cold surface and condense.

10. What happens to the temperature of the glass when condensation occurs on it? It warms up slightly.

11. What happens to the water level when the rate of evaporation equals the rate of condensation? The water level stays the same.

12. What causes clouds and fog? Condensation in the atmosphere due to the cooling of the air.

13. What is relative humidity? The amount of water vapor in the air compared with the limit for that temperature. Warm air can “hold” more water vapor than cold air.

14. What is the phase change during freezing? Is energy absorbed or released? Liquid to a solid Energy is released, warming the surroundings

15. Does the air get cooler or warmer when snowflakes form? Slightly warmer because the water droplets are releasing energy to freeze.

16. What is the phase change during melting? Do the surroundings warm up or cool down? Solid to a liquid The surroundings cool because energy needs to be absorbed for melting to occur.

17. What determines the boiling temperature of a pot of water? The amount of pressure present.

18. What happens to the temperature of boiling water when heat is continually supplied? It stays the same. Boiling is a “cooling process,” evaporation occurs at the surface.

19. Can water boil and freeze at the same time? Yes, in a vacuum chamber when all of the pressure is removed. Water will boil at such a low temperature that it will freeze.

20. What happens to the boiling temperature of water at higher altitudes? It’s lower because there’s less pressure on the water. The food needs to cook for a longer period of time because of the lower boiling temperature.

21. What’s the advantage of a pressure cooker? Pressure cookers raise the boiling temperature due to an increase in pressure. The water gets hotter so the food will cook faster.