CHAPTER 12 Review

A. Completing Concepts

1. At one time, heat was thought to be a fluid called __________ which flowed in and out of objects.

2. Heat is the energy transferred from one object to another because of a difference in __________.

3. The __________ of a substance is a measure of the average kinetic energy of the molecules of the substance.

4. __________ and __________ are the two liquids most commonly used in thermometers.

5. At -273° C, the average kinetic energy of the molecules in matter is __________.

6. The first law of thermodynamics states that the total increase in the thermal energy of a system is the sum of the work done on it and the __________ added to it.

7. The second law of thermodynamics indicates that heat spontaneously flows from a(n) __________ substance to a(n) __________ substance, never the reverse.

8. __________ is the “unavailability” of energy.

9. __________ is the proper unit for all energy, including heat.

10. The __________ of a substance is the amount of heat needed to raise the temperature of a unit mass of the substance through 1 degree.

11. The energy of heat is __________ when changed to another form.

12. __________ is the heat needed to change a unit mass of a substance at its melting temperature from a solid into a liquid.

13. To change 1.0 g of water at 100°C to steam at 100°C, __________ J are required.

B. UNDERSTANDING CONCEPTS

1. The thermal energy content of a swimming pool at a temperature of 20°C is __________ a cup of boiling water.

a. higher than

b. lower than

c. the same as

2. The Celsius degree is __________ the Kelvin.

a. larger than

b. smaller than

c. the same size as

3. At - 273°C, the molecules of a substance

a. retain no energy.

b. retain some energy.

c. gain some energy.

d. lose energy.

4. Compared to most substances, water requires __________ heat to raise its temperature.

a. more

b. less

5. The energy required to change a substance from a liquid to a gas is usually __________ the energy required to change the substance from a solid to a liquid.

a. more than

b. less than

c. the same as

6. In order to express a Celsius temperature reading in Kelvin, you must add __________ to the Celsius temperature.

a. - 273

b. 32

c. 212

d. 273

7. Substance A has twice the specific heat of substance B. Equal amounts of A and B are mixed together. If substance A gains 14 J of heat, substance B loses __________ J of heat.

a. 7

b. 14

c. 21

d. 28

8. The heat required to change 3.0 g of ice at 0.0°C to water at the same temperature is

a. 334 J.

b. 1002 J.

c. 2260 J.

d. 6780 J.

C. USING CONCEPTS

1.         a. Express - 35°C in K.

b. Express 85°C in K.

c. Express 435 K in °C.

d. Express 250 K in °C.

2. Calculate the energy needed to raise the temperature of 185 g of copper from 151°C to 201°C. Copper has a specific heat of 385 J/kg·C°.

3. 75 g of water at 81°C are mixed with 45 g of water at 21°C. Calculate the equilibrium temperature of the mixture. Assume no heat is lost or gained by the surroundings.

4. A 50.0-g piece of aluminum is heated in boiling water, then transferred into 150.0g of water at 19.5°C. After several minutes, the temperature of the water reaches equilibrium at 25°C. Assuming no heat is lost or gained by the surroundings, what is the specific heat of aluminum expressed in J/kg·C°?

5. How many joules of thermal energy must be applied to a 2.00-kg block of ice, initially at 0.0°C, to melt it and raise its temperature to 20.0°C? {Hf = 3.34 x 105 J/kg; C = 4.18 x 103 J/kg · K}

6. How many kilograms of water at 100.0°C can be converted to steam by the addition of 1.13 x 107 joules of thermal energy? {Hv = 2.26 x 106 J/kg}

7. Calculate the energy needed to change 25 g of ice at – 15.0°C to steam at 130.0°C. The specific heat of ice is 2.06 x 103 J/kg·C° and steam is 2.02 x 103 J/kg·C°.

If you have any questions, please email Ms. Cummings