Question 1

In an isochoric process, the internal (thermal) energy of an ideal gas decreases by 50 J. How much work does the gas do during this process?

Accepted Answer

A)  0.00 J 
B)  25 J 
C)  50 J 
D)  -25 J 
E)  -50 J 
A)  0.00 J 
B)  25 J 
C)  50 J 
D)  -25 J 
E)  -50 J

Question 2

An ideal gas increases in temperature from 22°C to 42°C by two different processes. In one process, the temperature increases at constant volume, and in the other process the temperature increases at constant pressure. Which of the following statements about this gas are correct? (There may be more than one correct choice.)

Accepted Answer

A)  The heat required to cause this temperature change is the same for both the constant-volume and the constant-pressure processes. 
B)  More heat is required for the constant-pressure process than for the constant-volume process. 
C)  The change in the internal (thermal) energy of the gas is the same for both the constant-volume and the constant-pressure processes. 
D)  The root-mean-square (thermal) speed of the gas molecules increases more during the constant-volume process than during the constant-pressure process. 
A)  The heat required to cause this temperature change is the same for both the constant-volume and the constant-pressure processes. 
B)  More heat is required for the constant-pressure process than for the constant-volume process. 
C)  The change in the internal (thermal) energy of the gas is the same for both the constant-volume and the constant-pressure processes. 
D)  The root-mean-square (thermal) speed of the gas molecules increases more during the constant-volume process than during the constant-pressure process.

Question 3

When a fixed amount of ideal gas goes through an isothermal expansion

Accepted Answer

A)  its internal (thermal) energy does not change. 
B)  the gas does no work. 
C)  no heat enters or leaves the gas. 
D)  its temperature must decrease. 
E)  its pressure must increase. 
A)  its internal (thermal) energy does not change. 
B)  the gas does no work. 
C)  no heat enters or leaves the gas. 
D)  its temperature must decrease. 
E)  its pressure must increase.

Question 4

A monatomic ideal gas undergoes an isothermal expansion at 300 K, as the volume increased from 0.03 m3 to 0.21 m3. The final pressure of the gas is 60 kPA. The ideal gas constant is R = 8.314 J/mol ∙ K. The change in the internal (thermal) energy of the gas is closest to

Accepted Answer

A)  0.00 kJ. 
B)  12 kJ. 
C)  25 kJ. 
D)  -12 kJ. 
E)  -25 kJ. 
A)  0.00 kJ. 
B)  12 kJ. 
C)  25 kJ. 
D)  -12 kJ. 
E)  -25 kJ.

Question 5

3.0 moles of an ideal gas with a molar heat capacity at constant volume of 4.9 cal/(mol∙K) and a molar heat capacity at constant pressure of 6.9 cal/(mol∙K) starts at 300 K and is heated at constant pressure to 320 K, then cooled at constant volume to its original temperature. How much heat flows into the gas during this two-step process?

Accepted Answer

A)  710 cal 
B)  -720 cal 
C)  0.00 cal 
D)  120 cal 
E)  -120 cal 
A)  710 cal 
B)  -720 cal 
C)  0.00 cal 
D)  120 cal 
E)  -120 cal

Question 6

An expansion process on an ideal diatomic gas has a linear path between the initial and final states on a pV diagram. The initial pressure is 300 kPa, the initial volume is 0.020 m3, and the initial temperature is 390 K. The final pressure is 160 kPa and the final temperature is 310K. The change in the internal (thermal) energy of the gas is closest to

Accepted Answer

A)  -3100 J. 
B)  -1800 J. 
C)  3100 J. 
D)  1800 J. 
E)  0.00 J. 
A)  -3100 J. 
B)  -1800 J. 
C)  3100 J. 
D)  1800 J. 
E)  0.00 J.

Question 7

When a gas undergoes an isothermal process, there is

Accepted Answer

A)  no change in the pressure of the gas. 
B)  no change in the temperature of the gas. 
C)  no change in the volume of the gas. 
D)  no work done by (or on) the gas. 
E)  no heat added to the gas. 
A)  no change in the pressure of the gas. 
B)  no change in the temperature of the gas. 
C)  no change in the volume of the gas. 
D)  no work done by (or on) the gas. 
E)  no heat added to the gas.

Question 8

How much work is done by 3.00 mol of ideal gas when it triples its volume at a constant temperature of 127°C? The ideal gas constant is R = 8.314 J/mol ∙ K.

Accepted Answer

A)  12.7 kJ 
B)  9.97 kJ 
C)  11.0 kJ 
D)  15.3 kJ 
E)  1.20 kJ 
A)  12.7 kJ 
B)  9.97 kJ 
C)  11.0 kJ 
D)  15.3 kJ 
E)  1.20 kJ

Question 9

The gas in a perfectly insulated system does work at a rate of 13 W. At what rate is the internal (thermal) energy of the gas changing?

Accepted Answer

A)  -13 W 
B)  13 W 
C)  0.00 W 
D)  6.5 W 
A)  -13 W 
B)  13 W 
C)  0.00 W 
D)  6.5 W

Question 10

The figure shows a pV diagram for 8.3 g of nitrogen gas (N2) in a sealed container. The temperature T1 of the gas in state 1 is 79°C. What are (a) the pressure p1 of the gas in state 1 and (b) the temperature T2 of the gas in state 2? The ideal gas constant is R = 8.314 J/mol ∙ K = 0.0821 L ∙ atm/mol ∙ K, and the ATOMIC weight of nitrogen is 14 g/mol.

Accepted Answer

A)  (a) 86 atm, (b) 700°C. 
B)  (a) 19 atm, (b) 700°C. 
C)  (a) 86 atm, (b) 160°C. 
D)  (a) 19 atm, (b) 160°C. 
A)  (a) 86 atm, (b) 700°C. 
B)  (a) 19 atm, (b) 700°C. 
C)  (a) 86 atm, (b) 160°C. 
D)  (a) 19 atm, (b) 160°C.

Question 11

An ideal gas is allowed to expand slowly at constant temperature to twice its original volume. During the expansion, the gas absorbs 200 kJ of heat.
(a) What is the change in the internal (thermal) energy of the gas during the expansion?
(b) How much work does the gas do during the expansion?

Accepted Answer

(A) ZERO

Question 12

An expansion process on an ideal diatomic gas has a linear path between the initial and final states on a pV diagram. The initial pressure is 300 kPa, the initial volume is 0.060 m3, and the initial temperature is 390 K. The ideal gas constant is R = 8.314 J/mol ∙ K. The final pressure is 150 kPa and the final temperature is 260K. The work done by the gas is closest to

Accepted Answer

A)  4500 J. 
B)  2300 J. 
C)  3400 J. 
D)  5600 J. 
E)  6800 J. 
A)  4500 J. 
B)  2300 J. 
C)  3400 J. 
D)  5600 J. 
E)  6800 J.

Exam 18: The First Law of Thermodynamics

In an isochoric process, the internal (thermal) energy of an ideal gas decreases by 50 J. How much work does the gas do during this process?

When a fixed amount of ideal gas goes through an isothermal expansion

A monatomic ideal gas undergoes an isothermal expansion at 300 K, as the volume increased from 0.03 m3 to 0.21 m3. The final pressure of the gas is 60 kPA. The ideal gas constant is R = 8.314 J/mol ∙ K. The change in the internal (thermal) energy of the gas is closest to

When a gas undergoes an isothermal process, there is

How much work is done by 3.00 mol of ideal gas when it triples its volume at a constant temperature of 127°C? The ideal gas constant is R = 8.314 J/mol ∙ K.

The gas in a perfectly insulated system does work at a rate of 13 W. At what rate is the internal (thermal) energy of the gas changing?

An ideal gas is allowed to expand slowly at constant temperature to twice its original volume. During the expansion, the gas absorbs 200 kJ of heat. (a) What is the change in the internal (thermal) energy of the gas during the expansion? (b) How much work does the gas do during the expansion?

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A monatomic ideal gas undergoes an isothermal expansion at 300 K, as the volume increased from 0.03 m³ to 0.21 m³. The final pressure of the gas is 60 kPA. The ideal gas constant is R = 8.314 J/mol ∙ K. The change in the internal (thermal) energy of the gas is closest to