Freezing: 0 o C 273 K 32 o F

1. The container on the left is cooler, the molecules move slower (have less kinetic energy) and exert a smaller pressure on the container walls compared to the molecules of the warmer container at right.

2. Boiling: 100 oC 373 K 212 oF Freezing: 0 oC 273 K 32 oF A temperature change of 1oC is the same as a temperature change of 1 K. Both of these are equal to a temperature change of 1.8 oF.

3. 1 calorie is the amount of heat energy needed to raise 1.0 gram of water by 1.0 oC.

4. 1 calories is the amount of heat energy needed to raise 1.0 gram of water by 1.0 oC. How much energy is need to raise 10 gm of water by 1.0 oC? How much energy is need to raise 5 gm of water by 1.0 oC? How much energy is need to raise 5 gm of water by 3.0 oC?

5. How much energy is need to raise 10 gm of water by 1.0 oC? 10 calories How much energy is need to raise 5 gm of water by 1.0 oC? 5 calories How much energy is need to raise 5 gm of water by 3.0 oC? 15 calories The heat capacity of an object is the total amount of heat energy needed to raise the temperature of an object by 1.0 oC The heat capacity of the ocean is huge and the heat capacity of a cup of coffee is small. The heat capacity of 10 gm of water is 10 calories/oC and that of 5 grams of water is 5 calorie/oC. Heat capacity is also called thermal inertia as it describes how hard it is to change an object’s temperature.

6. 1 calorie is the amount of heat energy needed to raise 1.0 gram of water by 1.0 oC. The specific heat capacity of water is 1.0 calorie/gm/oC The amount of heat energy required to raise 1.0 gm of rock by 1.0 oC is about 0.2 calories so the specific heat capacity of rock is only 0.2 calorie/gm/oC. Water has one of the highest specific heat capacities of normal substances. This makes it an excellent medium for storing solar energy. The idea is that it is hard to store heat energy in a material if the material gets hot. So, since water can hold a lot of energy (High heat capacity) without getting very hot, it is a perfect storage medium.

7. Table 2-1, p. 30

8. Object A has a large heat capacity relative to object B . • (Circle any of the correct statements) • For a given energy input, the temperature of object A will increase more than that of object B. • For a given energy loss, the temperature of object A will drop less than that of object B. • When both experience the same temperature increase the energy input into A is larger.

9. Object A has a large heat capacity relative to object B . • (Circle any of the correct statements) • For a given energy input, the temperature of object A will increase more than that of object B. • For a given energy loss, the temperature of object A will drop less than that of object B. • When both experience the same temperature increase the energy input into A is larger. • 2 and 3 are correct statements

10. States of Matter 1. Gas 2. Liquid 3. Solid

11. Molecules of a gas have a high average energy compared to molecules of a liquid or solid.

12. Molecules of a liquid have an intermediate average energy compared to molecules of a gas or solid.

13. Molecules of a soli have the lowest average energy compared to molecules of a liquid or gas.

14. It takes energy to convert ice into liquid water. That is it takes energy to melt ice. As ice in an ice water mixture melts the temperature doesn’t change. All of the energy going into the ice water id used to change ice into water. This energy is referred to as latent heat energy. Latent means hidden .

15. It takes energy to liquid water in water vapor. The Latent heat for evaporation comes from the environment. For example when you get out of the pool on a nice day you are likely to get goose bumps on your skin as water evaporates from your skin. Much of the latent energy needed for evaporation comes from your skin. For this reason evaporation is said to be a cooling process.

16. Sublimation is the process by which solid turns directly into vapor. As frost disappears on a cold day (less than 32 oF) in Eastern WA it is sublimating. The opposite of sublimation is deposition; vapor turning directly into ice like when frost forms.

17. As vapor condenses into liquid, energy is released into the environment. As cloud drop form the surrounding air actually warms. This release of latent heat energy into the environment via condensation is a fundamental energy source of hurricanes and thunderstorms. Snow formation and depositon also warm the surrounding environment.

18. When water evaporates from your body, energy is removed from or added to the water? When water evaporates from your body, energy is removed from or added to your body? When water freezes energy is removed from or added to the water?

19. When water evaporates from your body, energy is removed from or added to the water? When water evaporates from your body, energy is removed from or added to your body? When water freezes energy is removed from or added to the water?

20. The energy released into the environment as clouds form causes the air to warm which further enhance the vertical growth of clouds.

21. 3 mechanisms for Heat Transfer • Conduction • Convection • Radiation

23. Conduction: The energetic hot molecules collide with less energetic cooler molecules transferring energy fro hot to cold via molecular collisions.

24. Conduction through a wall, window, or slab of ice on a lake or ocean.

25. Relative Thermal Conductivities Silver 420 Aluminum 240 Water 0.57 Snow 0.20 Ice 2.2 Wood 0.15 Vacuum 0.0

26. Convection is the transfer of energy from hot to cold via the net flow of warm fluid (liquid or gas). In meteorology vertical air motion and heat transfer it referred to as convection and horizontal flow is advection.

27. Thermal convection developing in the afternoon cools the ground and warms the air above.

28. As air rises it expands because the pressure it feel gets smaller and smaller. Expanding air naturally cools. Try this! Open your mouth fairly wide and gently blow air onto your hand. It will likely feel warm. Now pucker and blow air rapidly onto you hand through a small opening in your mouth. It should feel a bit cooler.

29. The freezer compartment becomes very cold as the refrigeration fluid escapes through the expansion valve.

30. As air sinks it is compressed because the pressure it feel gets greater and greater. Compressed air naturally warms. Try this! Feel the bottom of your bicycle pump after you have been pumping air into your tire.

31. As the air filled tube is compressed the tissue paper ignites. In a diesel engine as the air fuel mixture is compressed rapidly it ignites. No need for spark plugs, rapid compression is enough to keep the engine running.

32. Expanding (rising) air coolsCompressing (sinking) air warms

34. Newton’s Law of cooling Hot objects lose heat energy Faster than Warmobjects Newton’s law of cooling applies to all three forms of heat transfer.

35. A cooling cup of coffee Newton’s law of cooling states that a cup of coffee cools of fast initially and then more gradually as it approaches room temperature.

36. A cup of coffee cools from 90°F to 80°F in 1.0 minute. If the same coffee starts out at 180 °F how long will it take to cool to 170 °F? a) More than 1 minute b) Less than 1 minute c) about 1 minute

37. A cup of coffee cools from 90°F to 80°F in 1.0 minute. If the same coffee starts out at 180 °F how long will it take to cool to 170 °F? a) More than 1 minute b) Less than 1 minute c) about 1 minute