1. Q18.1
A quantity of an ideal gas is contained in a balloon. Initially the gas temperature is 27°C.
You double the pressure on the balloon and change the temperature so that the balloon shrinks to one-quarter of its original volume. What is the new temperature of the gas?
1. 54°C
2. 27°C °C
4. –123°C
5. –198°C

2. A18.1
A quantity of an ideal gas is contained in a balloon. Initially the gas temperature is 27°C.
You double the pressure on the balloon and change the temperature so that the balloon shrinks to one-quarter of its original volume. What is the new temperature of the gas?
1. 54°C
2. 27°C °C
4. –123°C
5. –198°C

3. Q18.2
This pV–diagram shows two isotherms for the same amount of an ideal gas.
Which isotherm corresponds to the higher temperature?
1. curve #1
2. curve #2
3. answer depends on the particular temperatures in question
4. answer depends on the particular quantity of gas
5. both 3. and 4. are correct

4. A18.2
This pV–diagram shows two isotherms for the same amount of an ideal gas.
Which isotherm corresponds to the higher temperature?
1. curve #1
2. curve #2
3. answer depends on the particular temperatures in question
4. answer depends on the particular quantity of gas
5. both 3. and 4. are correct

5. Q18.3
Consider two specimens of ideal gas at the same temperature.
Specimen #1 has the same total mass as specimen #2, but the molecules in specimen #1 have greater molar mass than the molecules in specimen #2.
In which specimen is the total translational kinetic energy of the gas greater?
1. specimen #1
2. specimen #2
3. answer depends on the particular mass of gas
4. answer depends on the particular molar masses
5. both 3. and 4. are correct

6. A18.3
Consider two specimens of ideal gas at the same temperature.
Specimen #1 has the same total mass as specimen #2, but the molecules in specimen #1 have greater molar mass than the molecules in specimen #2.
In which specimen is the total translational kinetic energy of the gas greater?
1. specimen #1
2. specimen #2
3. answer depends on the particular mass of gas
4. answer depends on the particular molar masses
5. both 3. and 4. are correct

7. Q18.4
You have a quantity of ideal gas in a cylinder with rigid walls that prevents the gas from expanding or contracting. If you double the rms speed of molecules in the gas, the gas pressure
1. increases by a factor of 16
2. increases by a factor of 4
3. increases by a factor of 2
4. increases by a factor of 21/2

8. A18.4
You have a quantity of ideal gas in a cylinder with rigid walls that prevents the gas from expanding or contracting. If you double the rms speed of molecules in the gas, the gas pressure
1. increases by a factor of 16
2. increases by a factor of 4
3. increases by a factor of 2
4. increases by a factor of 21/2

9. Q18.5
The molar heat capacity at constant volume of diatomic hydrogen gas (H2) is 5R/2 at 500 K but only 3R/2 at 50 K. Why is this?
1. at 500 K the molecules can vibrate, while at 50 K they cannot
2. at 500 K the molecules cannot vibrate, while at 50 K they can
3. at 500 K the molecules can rotate, while at 50 K they cannot
4. at 500 K the molecules can rotate, while at 50 K they cannot

10. A18.5
The molar heat capacity at constant volume of diatomic hydrogen gas (H2) is 5R/2 at 500 K but only 3R/2 at 50 K. Why is this?
1. at 500 K the molecules can vibrate, while at 50 K they cannot
2. at 500 K the molecules cannot vibrate, while at 50 K they can
3. at 500 K the molecules can rotate, while at 50 K they cannot
4. at 500 K the molecules can rotate, while at 50 K they cannot

11. Q18.6
If the pressure of the atmosphere is below the triple-point pressure of a certain substance, that substance can exist (depending on the temperature)
1. as a liquid or as a vapor, but not as a solid
2. as a liquid or as a solid, but not as a vapor
3. as a solid or as a vapor, but not as a liquid
4. as a solid, a liquid, or a vapor

12. A18.6
If the pressure of the atmosphere is below the triple-point pressure of a certain substance, that substance can exist (depending on the temperature)
1. as a liquid or as a vapor, but not as a solid
2. as a liquid or as a solid, but not as a vapor
3. as a solid or as a vapor, but not as a liquid
4. as a solid, a liquid, or a vapor