Sections
Chapter Review

# Chapter Review

### Concept Items

#### 12.1Zeroth Law of Thermodynamics: Thermal Equilibrium

1.

When are two bodies in thermal equilibrium?

1. When they are in thermal contact and are at different pressures
2. When they are not in thermal contact but are at the same pressure
3. When they are not in thermal contact but are at different temperatures
4. When they are in thermal contact and are at the same temperature
2.

What is thermal contact?

1. Two objects are said to be in thermal contact when they are in contact with each other in such a way that the transfer of energy by heat can occur between them.
2. Two objects are said to be in thermal contact when they are in contact with each other in such a way that the transfer of energy by mass can occur between them.
3. Two objects are said to be in thermal contact when they neither lose nor gain energy by heat. There is no transfer of energy between them.
4. Two objects are said to be in thermal contact when they only gain energy by heat. There is transfer of energy between them.
3.

To which mathematical property is the zeroth law of thermodynamics similar?

1. Associative property
2. Commutative property
3. Distributive property
4. Transitive property

#### 12.2First law of Thermodynamics: Thermal Energy and Work

4.
Why does thermal expansion occur?
1. An increase in temperature causes intermolecular distances to increase.
2. An increase in temperature causes intermolecular distances to decrease.
3. An increase in temperature causes an increase in the work done on the system.
4. An increase in temperature causes an increase in the work done by the system.
5.
How does pressure-volume work relate to heat and internal energy of a system?
1. The energy added to a system by heat minus the change in the internal energy of that system is equal to the pressure-volume work done by the system.
2. The sum of the energy released by a system by heat and the change in the internal energy of that system is equal to the pressure-volume work done by the system.
3. The product of the energy added to a system by heat and the change in the internal energy of that system is equal to the pressure-volume work done by the system.
4. If the energy added to a system by heat is divided by the change in the internal energy of that system, the quotient is equal to the pressure-volume work done by the system.
6.

On what does internal energy depend?

1. The path of energy changes in the system
2. The state of the system
3. The size of the system
4. The shape of the system
7.

The first law of thermodynamics helps us understand the relationships among which three quantities?

1. Heat, work, and internal energy
2. Heat, work, and external energy
3. Heat, work, and enthalpy
4. Heat, work, and entropy

#### 12.3Second Law of Thermodynamics: Entropy

8.

Air freshener is sprayed from a bottle. The molecules spread throughout the room and cannot make their way back into the bottle. Why is this the case?

1. The entropy of the molecules increases.
2. The entropy of the molecules decreases.
3. The heat content (enthalpy, or total energy available for heat) of the molecules increases.
4. The heat content (enthalpy, or total energy available for heat) of the molecules decreases.
9.

Give an example of entropy as experienced in everyday life.

1. rotation of Earth
2. formation of a solar eclipse
3. filling a car tire with air
4. motion of a pendulum bob

#### 12.4Applications of Thermodynamics: Heat Engines, Heat Pumps, and Refrigerators

10.

What is the quality by which air conditioners are judged?

1. The amount of energy generated by heat from a hot environment, compared with the required work input
2. The amount of energy transferred by heat from a cold environment, compared with the required work input
3. The amount of energy transferred by heat from a hot environment, compared with the required work output
4. The amount of energy transferred by heat from a cold environment, compared with the required work output
11.

Why is the efficiency of a heat engine never 100 percent?

1. Some energy is always gained by heat from the environment.
2. Some energy is always lost by heat to the environment.
3. Work output is always greater than energy input.
4. Work output is infinite for any energy input.
12.

What is a cyclic process?

1. A process in which the system returns to its original state at the end of the cycle
2. A process in which the system does not return to its original state at the end of the cycle
3. A process in which the system follows the same path for every cycle
4. A process in which the system follows a different path for every cycle
13.

What is the advantage of a heat pump as opposed to burning fuel (as in a fireplace) for keeping warm?

1. A heat pump supplies energy by heat from the cold, outside air.
2. A heat pump supplies energy generated by the work done.
3. A heat pump supplies energy by heat from the cold, outside air and also from the energy generated by the work done.
4. A heat pump supplies energy not by heat from the cold, outside air, nor from the energy generated by the work done, but from more accessible sources.
14.

What is thermal efficiency of an engine? Can it ever be 100 percent? Why or why not?

1. Thermal efficiency is the ratio of the output (work) to the input (heat). It is always 100 percent.
2. Thermal efficiency is the ratio of the output (heat) to the input (work). It is always 100 percent.
3. Thermal efficiency is the ratio of the output (heat) to the input (work). It is never 100 percent.
4. Thermal efficiency is the ratio of the output (work) to the input (heat). It is never 100 percent.
15.

When would 100 percent thermal efficiency be possible?

1. When all energy is transferred by heat to the environment
2. When mass transferred to the environment is zero
3. When mass transferred to the environment is at a maximum
4. When no energy is transferred by heat to the environment
16.

A coal power station functions at 40.0 percent efficiency. What is the amount of work it does if it takes in 1.20×1012 J by heat?

1. 3×1010 J
2. 4.8×1011 J
3. 3×1012 J
4. 4.8×1013 J
17.

A heat engine functions with 70.7 percent thermal efficiency and consumes 12.0 kJ from heat daily. If its efficiency were raised to 75.0 percent, how much energy from heat would be saved daily, while providing the same output?

1. −10.8 kJ
2. −1.08 kJ
3. 0.7 kJ
4. 7 kJ

### Critical Thinking Items

#### 12.1Zeroth Law of Thermodynamics: Thermal Equilibrium

18.
What are the necessary conditions for energy transfer by heat to occur between two bodies through the process of conduction?
1. They should be at the same temperature, and they should be in thermal contact.
2. They should be at the same temperature, and they should not be in thermal contact.
3. They should be at different temperatures, and they should be in thermal contact.
4. They should be at different temperatures, and they should not be in thermal contact.
19.

Oil is heated in a pan on a hot plate. The pan is in thermal equilibrium with the hot plate and also with the oil. The temperature of the hot plate is 150 °C . What is the temperature of the oil?

1. 160 °C
2. 150 °C
3. 140 °C
4. 130 °C

#### 12.2First law of Thermodynamics: Thermal Energy and Work

20.
When an inflated balloon experiences a decrease in size, the air pressure inside the balloon remains nearly constant. If there is no transfer of energy by heat to or from the balloon, what physical change takes place in the balloon?
1. The average kinetic energy of the gas particles decreases, so the balloon becomes colder.
2. The average kinetic energy of the gas particles increases, so the balloon becomes hotter.
3. The average potential energy of the gas particles decreases, so the balloon becomes colder.
4. The average potential energy of the gas particles increases, so the balloon becomes hotter.
21.
When heat adds energy to a system, what is likely to happen to the pressure and volume of the system?
1. Pressure and volume may both decrease with added energy.
2. Pressure and volume may both increase with added energy.
3. Pressure must increase with added energy, while volume must remain constant.
4. Volume must decrease with added energy, while pressure must remain constant.
22.
If more energy is transferred into the system by net heat as compared to the net work done by the system, what happens to the difference in energy?
1. It is transferred back to its surroundings.
2. It is stored in the system as internal energy.
3. It is stored in the system as potential energy.
4. It is stored in the system as entropy.
23.

Air is pumped into a car tire, causing its temperature to increase. In another tire, the temperature increase is due to exposure to the sun. Is it possible to tell what caused the temperature increase in each tire? Explain your answer.

1. No, because it is a chemical change, and the cause of that change does not matter; the final state of both systems are the same.
2. Although the final state of each system is identical, the source is different in each case.
3. No, because the changes in energy for both systems are the same, and the cause of that change does not matter; the state of each system is identical.
4. Yes, the changes in the energy for both systems are the same, but the causes of that change are different, so the states of each system are not identical.
24.

How does the transfer of energy from the sun help plants?

1. Plants absorb solar energy from the sun and utilize it during the fertilization process.
2. Plants absorb solar energy from the sun and utilize it during the process of photosynthesis to turn it into plant matter.
3. Plants absorb solar energy from the sun and utilize it to increase the temperature inside them.
4. Plants absorb solar energy from the sun and utilize it during the shedding of their leaves and fruits.

#### 12.3Second Law of Thermodynamics: Entropy

25.

If an engine were constructed to perform under ideal conditions such that there would be no losses due to friction, what would be its efficiency?

1. It would be 0 percent.
2. It would be less than 100 percent.
3. It would be 100 percent.
4. It would be greater than 100 percent.
26.

Entropy never decreases in a spontaneous process. Give an example to support this statement.

1. The transfer of energy by heat from colder bodies to hotter bodies is a spontaneous process in which the entropy of the system of bodies increases.
2. The melting of an ice cube placed in a room causes an increase in the entropy of the room.
3. The dissolution of salt in water is a spontaneous process in which the entropy of the system increases.
4. A plant uses energy from the sun and converts it into sugar molecules by the process of photosynthesis.

### Problems

#### 12.2First law of Thermodynamics: Thermal Energy and Work

27.
Some amount of energy is transferred by heat into a system. The net work done by the system is $50J$, while the increase in its internal energy is $30J$. What is the amount of net heat?
1. $−80J$
2. $−20J$
3. $20J$
4. $80J$
28.
Eighty joules are added by heat to a system, while it does $20J$ of work. Later, $30J$ are added by heat to the system, and it does $40J$ of work. What is the change in the system’s internal energy?
1. $30J$
2. $50J$
3. $60J$
4. $110J$

#### 12.4Applications of Thermodynamics: Heat Engines, Heat Pumps, and Refrigerators

29.

You have been tasked to design and construct a thermometer that works on the principle of thermal expansion. There are four materials available for you to test, each of which will find use under different sets of conditions and temperature ranges:

Materials
• Four sample materials with similar mass or volume: copper, steel, water, and alcohol (ethanol or isopropanol)
• Oven or similar heating source
• Instrument (e.g., meter ruler, Vernier calipers, or micrometer) for measuring changes in dimension
• Balance for measuring mass
Procedure
1. Design a safe experiment to analyze the thermal expansion properties of each material.
2. Write down the materials needed for your experiment and the procedure you will follow. Make sure that you include every detail so that the experiment can be repeated by others.
3. Select an appropriate material to measure temperature over a predecided temperature range, and give reasons for your choice.
4. Calibrate your instrument to measure temperature changes accurately.
1. Which physical quantities are affected by temperature change and thermal expansion?
2. How do such properties as specific heat and thermal conductivity affect the use of each material as a thermometer?
3. Does a change of phase take place for any of the tested materials over the temperature range to be examined?
4. What are your independent and dependent variables for this series of tests? Which variables need to be controlled in the experiment?
5. What are your sources of error?
6. Can all the tested materials be used effectively in the same ranges of temperature? Which applications might be suitable for one or more of the tested substances but not the others?