Download Study Guide Thermodynamics

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THERMAL ENERGY
Vocabulary Review
Write the term that correctly completes the statement. Use each term once.
convection
heat engine
second law of thermodynamics
entropy
heat of fusion
specific heat
first law of thermodynamics
heat of vaporization
thermal conduction
heat
radiation
thermal equilibrium
1. _________________________
____ is the state at which the rate of thermal energy transfer
between two objects is equal and the objects are at the same
temperature.
2. _________________________
The transfer of thermal energy between objects is called ____ .
3. _________________________
The amount of energy required to raise the temperature of one
unit mass of a substance by one temperature unit is the ____ of
the substance.
4. _________________________
The amount of energy needed to melt 1 kg of a substance is the
____ .
5. _________________________
The ____ states that the change in thermal energy of an object
equals the heat added to the object minus the work done by
the object.
6. _________________________
____ is the transfer of kinetic energy when particles collide.
7. _________________________
____ is a measure of the energy dispersal of a system.
8. _________________________
A device that converts thermal energy to mechanical energy is
a(n) ____ .
9. _________________________
The ____ states that natural processes go in a direction that
increases the total entropy of the universe.
10. _________________________
____ is the motion of a fluid caused by temperature differences.
11. _________________________
The amount of energy required to convert 1 kg of a substance
from a liquid to a gas is the ____ .
12. _________________________
The transfer of energy by electromagnetic waves is called ____ .
Chapter 12  Thermal Energy
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SECTION 1 Temperature, Heat, and Thermal Energy
In your textbook, read about the theory of thermal energy and temperature.
For each statement below, write true or rewrite the italicized part to make the statement true.
1. _________________________
The temperature of an object is a measure of the total kinetic
energy of the particles.
2. _________________________
The thermal energy in an object depends on the number of
particles in the object and the temperature of the object.
3. _________________________
Two bodies are in rotational equilibrium if they are at the same
temperature.
4. _________________________
A Kelvin is equal in magnitude to a Celsius degree.
5. _________________________
Absolute zero is equal to 0°C.
6. _________________________
The freezing point of water is 0°C or 212 K.
7. _________________________
Absolute zero is the point at which a substance has minimal
thermal energy.
In your textbook, read about specific heat.
For each term on the left, write the letter of the corresponding item.
8. _____ unit of specific heat
a. K
9. _____ heat
b. S
10. _____ degree Celsius
c. T
11. _____ Kelvin
d. C
12. _____ entropy
e. Q
13. _____ energy change
f. J/(kg•K)
14. _____ temperature change
g. E
Answer the following questions. Use complete sentences.
15. Why is the Kelvin temperature scale rather than the Celsius temperature scale used in science?
Use “kinetic energy” in your answer.
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16. The diagram shows the construction of the inner liner of a
vacuum bottle. How does a vacuum bottle prevent the transfer
of thermal energy:
a.
by conduction?
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b.
by convection?
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c.
by radiation?
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17. What is the specific heat of a metal if it takes 15,000 J of heat to raise the temperature of a
620-g sample from 15.0C to 85.0C?
In your textbook, read about calorimetry.
Use the following information to answer questions 18–21.
A student uses a foam cup as a calorimeter. The student places 100.0 g of water at 20C in the cup.
The student adds 100.0 g of lead shot at 120C to the cup. The water and shot are then allowed to
reach thermal equilibrium. The specific heat of lead is 130 J/(kg•K).
18. Is Q for the water positive or negative?
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19. Is Q for the lead shot positive or negative?
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20. Assuming that no thermal energy is lost to the surroundings, how does the total energy of the
system compare with the total energy of the water and lead before mixing?
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21. What is the final temperature of the water at thermal equilibrium?
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SECTION 2 Changes of State and Thermodynamics
In your textbook, read about changes of state.
Circle the letter of the choice that best completes the statement or answers the question.
1. The energy needed to melt 1 kg of a substance is called the _____ .
a. heat of vaporization
c. heat of fusion
b. melting point
d. freezing point
2. The temperature at which all added thermal energy is used to change a liquid to a gas is the
_____ .
a. boiling point
c. heat of fusion
b. melting point
d. heat of vaporization
3. How does the amount of energy absorbed by 1 g of ice as it melts compare to the amount of
energy released by 1 g of water as it freezes?
a. More energy is released by the ice than is absorbed by the water.
b. More energy is absorbed by the water than is released by the ice.
c. The amounts of energy absorbed and released depend on the surrounding temperature.
d. They are the same.
4. Which equation correctly relates heat, mass, and the heat of vaporization?
a. Q  m  Hv
c. Q  m/Hv
b. Q  mHv
d. Q  Hv/m
5. As a liquid changes to a gas, _____ .
a. both its kinetic and potential
energy increase
c. only its potential energy increases
b. only its kinetic energy increases
d. neither its kinetic nor potential energy increases
6. How does the amount of energy needed to melt 1 kg of ice at 0C compare to the amount of
energy needed to change 1 kg of water to steam at 100C? The heat of fusion of water is
3.34105 J/kg, and the heat of vaporization of water is 2.26106 J/kg.
a. It takes about two-thirds as much energy to boil the water as to melt the ice.
b. It takes the same amount of energy to boil the water and melt the ice.
c. It takes about two-thirds as much energy to melt the ice as to boil the water.
d. It takes more than six times as much energy to boil the water as to melt the ice.
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Answer the following questions. Show your calculations.
7. How much ice at 273 K can be melted by 5.00  103 J?
8. A 2.00  102 g sample of water at 60.0C is heated to steam at 140.0C.
a.
How much heat is absorbed?
b.
How much energy would be released if the steam at 140.0°C were cooled to water at
60.0C?
In your textbook, read about the first law of thermodynamics, the second law of thermodynamics, and entropy.
Answer the following questions. Use complete sentences.
9. State the first law of thermodynamics.
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10. Some people think that they can cool off a hot kitchen by leaving the refrigerator door open.
Why is that not true?
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11. When paint dries, does its entropy increase or decrease? Is this an instance where the second
law of thermodynamics does not apply? Explain your answer.
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For each statement, circle 1 or 2 to indicate whether the statement relates more closely to the first law of
thermodynamics or the second law of thermodynamics.
12. The total entropy of the universe tends to increase. (1) (2)
13. A change in the thermal energy of a system depends on the work done by the system and the
heat added to a system. (1) (2)
14. Thermal energy flows spontaneously from hot objects to cold objects. (1) (2)
15. The amount of useful energy tends to decrease. (1) (2)
16. A heat engine converts thermal energy to mechanical energy. (1) (2)
17. Using mechanical energy, a refrigerator removes thermal energy from warmer bodies. (1) (2)
18. The moving parts in an automobile engine generate waste heat. (1) (2)
Answer the following questions. Use complete sentences.
19. Explain why a heat engine must have a heat sink.
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20. How does energy efficiency relate to the first and second laws of thermodynamics?
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21. Why is it important for appliance and automobile manufacturers to make their products as
energy-efficient as possible?
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