Question 1

The temperature of a quantity of an ideal gas is

Accepted Answer

A)  one measure of its ability to transfer thermal energy to another body. 
B)  proportional to the average molecular kinetic energy of the molecules. 
C)  proportional to the internal energy of the gas. 
D)  correctly described by all the statements above. 
E)  correctly described only by (a) and (b) above. 
A)  one measure of its ability to transfer thermal energy to another body. 
B)  proportional to the average molecular kinetic energy of the molecules. 
C)  proportional to the internal energy of the gas. 
D)  correctly described by all the statements above. 
E)  correctly described only by (a) and (b) above. D

Question 2

According to kinetic theory, a typical gas molecule in thermal equilibrium at room temperature has a kinetic energy K = 6.00 × 10−21 J, regardless of mass. Estimate the speed at room temperature of a hydrogen molecule H2 (m = 3.34 × 10−27 kg) and a xenon atom (m = 2.00 × 10−25 kg). [kB = 1.38 × 10−23 J/K]

Accepted Answer

1 895 m/s, 245 m/s

Question 3

When we consider a thin horizontal layer of the atmosphere, of thickness dy, of area A, with pressure P on the bottom, with an average mass m per molecule, and nV molecules per unit volume, the magnitude of the difference of the pressure at the top and bottom of the layer is given by dP =

Accepted Answer

A)  mgdy. 
B)  mgnVdy. 
C)  mgAdy. 
D)  mgnVAdy. 
E)  mgnVAPdy. 
A)  mgdy. 
B)  mgnVdy. 
C)  mgAdy. 
D)  mgnVAdy. 
E)  mgnVAPdy. B

Question 4

The relation PV = nRT holds for all ideal gases. The additional relation PVγ holds for an adiabatic process. The figure below shows two curves: one is an adiabat and one is an isotherm. Each starts at the same pressure and volume. Which statement is correct? (Note: "∝" means "is proportional to".)

Accepted Answer

A)  Isotherm:
  ; Adiabat:
  : A is both an isotherm and an adiabat. 
B)  Isotherm:
  ; Adiabat:
  : B is an isotherm, A is an adiabat. 
C)  Isotherm:
  ; Adiabat:
  : A is an isotherm, B is an adiabat. 
D)  Isotherm:
  ; Adiabat:
  : B is both an isotherm and an adiabat. 
E)  cannot answer without additional information about the starting temperature. 
A)  Isotherm:
  ; Adiabat:
  : A is both an isotherm and an adiabat. 
B)  Isotherm:
  ; Adiabat:
  : B is an isotherm, A is an adiabat. 
C)  Isotherm:
  ; Adiabat:
  : A is an isotherm, B is an adiabat. 
D)  Isotherm:
  ; Adiabat:
  : B is both an isotherm and an adiabat. 
E)  cannot answer without additional information about the starting temperature.

Question 5

During the volcanic eruption of Mt. Pelee in 1902, an incredibly hot "burning cloud" rolled down the mountain and incinerated the town of Saint-Pierre. From the damage done, the temperature in the cloud was estimated at 700°C. If the air temperature was 20°C and a mole of air is 29 grams, estimate the molecular weight of the gas in the "burning cloud" that made it heavier than the surrounding air. (As a follow-on, estimate the most probable composition of the cloud. Some typical volcanic gases are H2S, SO2, H2SO4, CO2, NO.)

Accepted Answer

96, H₂SO₄ (s

Question 6

Nitrogen gas is heated by a pulsed laser to 50 000 K. If the diameter of the nitrogen atoms is assumed to be 1.0 × 10−10 m, and the pressure is 1.0 atm, what is the mean free path?

Accepted Answer

A)  1.5 × 10−4 m 
B)  1.5 × 10−7 m 
C)  1.5 × 10−10 m 
D)  1.5 × 10−14 m 
E)  1.5 × 10−2 m 
A)  1.5 × 10−4 m 
B)  1.5 × 10−7 m 
C)  1.5 × 10−10 m 
D)  1.5 × 10−14 m 
E)  1.5 × 10−2 m

Question 7

Air expands adiabatically (no heat in, no heat out) from T = 300 K and P = 100 atm to a final pressure of 1 atm. Treat the gas as ideal with γ = 1.4, and determine the final temperature. Compare your result to the boiling points of nitrogen (77.4 K) and oxygen (90.2 K). Could this method result in the liquification of air?

Accepted Answer

80.5 K, so

Question 8

When we say that the speed of sound is measured under adiabatic conditions we assume that

Accepted Answer

A)  the time associated with heat conduction is slow relative to the speed of the wave. 
B)  no heat can flow between the system and its surroundings. 
C)  the speed of the wave is directly proportional to the bulk modulus. 
D)  the speed of the wave is proportional to the square root of the bulk modulus. 
E)  air is an ideal gas. 
A)  the time associated with heat conduction is slow relative to the speed of the wave. 
B)  no heat can flow between the system and its surroundings. 
C)  the speed of the wave is directly proportional to the bulk modulus. 
D)  the speed of the wave is proportional to the square root of the bulk modulus. 
E)  air is an ideal gas.

Question 9

Find the specific heat (in cal/mole K) of a gas kept at constant volume when it takes 1.0 × 104 J of heat to raise the temperature of 5.0 moles of the gas 200 K above the initial temperature.

Accepted Answer

A)  7.5 
B)  5.0 
C)  2.4 
D)  10 
E)  20 
A)  7.5 
B)  5.0 
C)  2.4 
D)  10 
E)  20

Question 10

The molar specific heat at constant volume at 0°C of an ideal diatomic gas is

Accepted Answer

A) 
  . 
B)  R. 
C) 
  . 
D)  2R. 
E) 
  . 
A) 
  . 
B)  R. 
C) 
  . 
D)  2R. 
E) 
  .

Question 11

One mole of hydrogen, one mole of nitrogen and one mole of oxygen are held in a 22.4 × 103 cm3 enclosed vessel at 20°C. The pressure in the vessel, in N/m2, is

Accepted Answer

A)  109. 
B)  304. 
C)  326. 
D)  1.09 × 105. 
E)  3.26 × 105. 
A)  109. 
B)  304. 
C)  326. 
D)  1.09 × 105. 
E)  3.26 × 105.

Question 12

The molar specific heat at constant volume at 0°C of an ideal monatomic gas is

Accepted Answer

A) 
  . 
B)  R. 
C) 
  . 
D)  2R. 
E) 
  . 
A) 
  . 
B)  R. 
C) 
  . 
D)  2R. 
E) 
  .

Question 13

A 50-gram sample of dry ice (solid CO2) is placed in a 4-liter container. The system is sealed and allowed to reach room temperature (20°C). By approximately how much does the pressure inside the container increase when the dry ice turns to gas? (Ignore the initial volume of the sample.)

Accepted Answer

the pressu

Question 14

The root mean square speed of a gas molecule is greater than the average speed, because the former gives a greater weight to

Accepted Answer

A)  lighter molecules. 
B)  heavier molecules. 
C)  lower speeds. 
D)  higher speeds. 
E)  more probable speeds. 
A)  lighter molecules. 
B)  heavier molecules. 
C)  lower speeds. 
D)  higher speeds. 
E)  more probable speeds.

Question 15

Assume 3.0 moles of a diatomic gas has an internal kinetic energy of 10 kJ. Determine the temperature of the gas after it has reached equilibrium.

Accepted Answer

A)  270 K 
B)  160 K 
C)  800 K 
D)  1 550 K 
E)  400 K 
A)  270 K 
B)  160 K 
C)  800 K 
D)  1 550 K 
E)  400 K

Question 16

The specific heat of an ideal gas at constant pressure is greater than the specific heat of an ideal gas at constant volume because

Accepted Answer

A)  work is done by a gas at constant pressure. 
B)  work is done by a gas at constant volume. 
C)  no work is done by a gas at constant pressure. 
D)  the temperature remains constant for a gas at constant pressure. 
E)  the temperature remains constant for a gas at constant volume. 
A)  work is done by a gas at constant pressure. 
B)  work is done by a gas at constant volume. 
C)  no work is done by a gas at constant pressure. 
D)  the temperature remains constant for a gas at constant pressure. 
E)  the temperature remains constant for a gas at constant volume.

Question 17

If CP for an ideal gas is 35.4 J/mol⋅K, which of the following is CV for this gas?

Accepted Answer

A)  12.5 J/mol⋅K 
B)  20.8 J/mol⋅K 
C)  29.1 J/mol⋅K 
D)  27.1 J/mol⋅K 
E)  43.4 J/mol⋅K 
A)  12.5 J/mol⋅K 
B)  20.8 J/mol⋅K 
C)  29.1 J/mol⋅K 
D)  27.1 J/mol⋅K 
E)  43.4 J/mol⋅K

Question 18

The air in an automobile engine at 20°C is compressed from an initial pressure of 1.0 atm and a volume of 200 cm3 to a volume of 20 cm3. Find the temperature if the air behaves like an ideal gas (γ = 1.4) and the compression is adiabatic.

Accepted Answer

A)  730°C 
B)  460°C 
C)  25°C 
D)  50°C 
E)  20°C 
A)  730°C 
B)  460°C 
C)  25°C 
D)  50°C 
E)  20°C

Question 19

Suppose a box contains about 5.0 × 1021 hydrogen atoms at room temperature (21°C). Determine the thermal energy of these atoms.

Accepted Answer

A)  10 J 
B)  20 J 
C)  30 J 
D)  5.0 J 
E)  1.0 J 
A)  10 J 
B)  20 J 
C)  30 J 
D)  5.0 J 
E)  1.0 J

Question 20

Two tanks of gas, one of hydrogen, H2, and one of helium, He, contain equal numbers of moles of gas. The gram-molecular mass of He is twice that of H2. Both tanks of gas are at the same temperature, 293 K. Which statement(s) below is(are) correct when we ignore vibrational motion?

Accepted Answer

A)  The total internal energy of the hydrogen is the same as that of the helium. 
B)  The total internal energy of the hydrogen is 1.4 times that of the helium. 
C)  The total internal energy of the helium is 1.4 times that of the hydrogen. 
D)  The total internal energy of the hydrogen is 1.67 times that of the helium. 
E)  The total internal energy of the helium is 1.67 times that of the hydrogen. 
A)  The total internal energy of the hydrogen is the same as that of the helium. 
B)  The total internal energy of the hydrogen is 1.4 times that of the helium. 
C)  The total internal energy of the helium is 1.4 times that of the hydrogen. 
D)  The total internal energy of the hydrogen is 1.67 times that of the helium. 
E)  The total internal energy of the helium is 1.67 times that of the hydrogen.

Exam 21: The Kinetic Theory of Gases

The temperature of a quantity of an ideal gas is

When we consider a thin horizontal layer of the atmosphere, of thickness dy, of area A, with pressure P on the bottom, with an average mass m per molecule, and nV molecules per unit volume, the magnitude of the difference of the pressure at the top and bottom of the layer is given by dP =

Nitrogen gas is heated by a pulsed laser to 50 000 K. If the diameter of the nitrogen atoms is assumed to be 1.0 × 10−10 m, and the pressure is 1.0 atm, what is the mean free path?

When we say that the speed of sound is measured under adiabatic conditions we assume that

Find the specific heat (in cal/mole K) of a gas kept at constant volume when it takes 1.0 × 104 J of heat to raise the temperature of 5.0 moles of the gas 200 K above the initial temperature.

The molar specific heat at constant volume at 0°C of an ideal diatomic gas is

One mole of hydrogen, one mole of nitrogen and one mole of oxygen are held in a 22.4 × 103 cm3 enclosed vessel at 20°C. The pressure in the vessel, in N/m2, is

The molar specific heat at constant volume at 0°C of an ideal monatomic gas is

A 50-gram sample of dry ice (solid CO2) is placed in a 4-liter container. The system is sealed and allowed to reach room temperature (20°C). By approximately how much does the pressure inside the container increase when the dry ice turns to gas? (Ignore the initial volume of the sample.)

The root mean square speed of a gas molecule is greater than the average speed, because the former gives a greater weight to

Assume 3.0 moles of a diatomic gas has an internal kinetic energy of 10 kJ. Determine the temperature of the gas after it has reached equilibrium.

The specific heat of an ideal gas at constant pressure is greater than the specific heat of an ideal gas at constant volume because

If CP for an ideal gas is 35.4 J/mol⋅K, which of the following is CV for this gas?

The air in an automobile engine at 20°C is compressed from an initial pressure of 1.0 atm and a volume of 200 cm3 to a volume of 20 cm3. Find the temperature if the air behaves like an ideal gas (γ = 1.4) and the compression is adiabatic.

Suppose a box contains about 5.0 × 1021 hydrogen atoms at room temperature (21°C). Determine the thermal energy of these atoms.

Two tanks of gas, one of hydrogen, H2, and one of helium, He, contain equal numbers of moles of gas. The gram-molecular mass of He is twice that of H2. Both tanks of gas are at the same temperature, 293 K. Which statement(s) below is(are) correct when we ignore vibrational motion?

Physics and Measurement

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The Laws of Motion

Circular Motion and Other Applications of Newtons Laws

Energy of a System

Conservation of Energy

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Rotation of a Rigid Object About a Fixed Axis

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Gausss Law

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Image Formation

Wave Optics

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Introduction to Quantum Physics

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When we consider a thin horizontal layer of the atmosphere, of thickness dy, of area A, with pressure P on the bottom, with an average mass m per molecule, and n_V molecules per unit volume, the magnitude of the difference of the pressure at the top and bottom of the layer is given by dP =

Nitrogen gas is heated by a pulsed laser to 50 000 K. If the diameter of the nitrogen atoms is assumed to be 1.0 × 10−¹⁰ m, and the pressure is 1.0 atm, what is the mean free path?

Find the specific heat (in cal/mole K) of a gas kept at constant volume when it takes 1.0 × 10⁴ J of heat to raise the temperature of 5.0 moles of the gas 200 K above the initial temperature.

One mole of hydrogen, one mole of nitrogen and one mole of oxygen are held in a 22.4 × 10³ cm³ enclosed vessel at 20°C. The pressure in the vessel, in N/m², is

A 50-gram sample of dry ice (solid CO₂) is placed in a 4-liter container. The system is sealed and allowed to reach room temperature (20°C). By approximately how much does the pressure inside the container increase when the dry ice turns to gas? (Ignore the initial volume of the sample.)

If C_P for an ideal gas is 35.4 J/mol⋅K, which of the following is C_V for this gas?

The air in an automobile engine at 20°C is compressed from an initial pressure of 1.0 atm and a volume of 200 cm³ to a volume of 20 cm³. Find the temperature if the air behaves like an ideal gas (γ = 1.4) and the compression is adiabatic.

Suppose a box contains about 5.0 × 10²¹ hydrogen atoms at room temperature (21°C). Determine the thermal energy of these atoms.

Two tanks of gas, one of hydrogen, H₂, and one of helium, He, contain equal numbers of moles of gas. The gram-molecular mass of He is twice that of H₂. Both tanks of gas are at the same temperature, 293 K. Which statement(s) below is(are) correct when we ignore vibrational motion?