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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
c. about the same
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°.
