Deck 4: The Kinetic Theory of Gases

Question 1

An ideal gas occupies 12 liters at 293 K and 1 atm (76 cm Hg). Its temperature is now raised to 373 K and its pressure increased to 215 cm Hg. The new volume is:

A) 0.2 liters
B) 5.4 liters
C) 13.6 liters
D) 20.8 liters
E) none of these

Answer 1

5.4 liters

Question 2

An air bubble doubles in volume as it rises from the bottom of a lake (1000 kg/m³). Ignoring any temperature changes, the depth of the lake is:

A) 21 m
B) 0.76 m
C) 4.9 m
D) 10 m
E) 0.99 m

Answer 2

10 m

Question 3

An isothermal process for an ideal gas is represented on a p-V diagram by:

A) a horizontal line
B) a vertical line
C) a portion of an ellipse
D) a portion of a parabola
E) a hyperbola

Answer 3

a hyperbola

Question 4

A real gas is changed slowly from state 1 to state 2. During this process no work is done on or by the gas. This process must be:

A) isothermal
B) adiabatic
C) isovolumic
D) isobaric
E) a closed cycle with point 1 coinciding with point 2

Question 5

In order that a single process be both isothermal and isobaric:

A) one must use an ideal gas
B) such a process is impossible
C) a change of phase is essential
D) one may use any real gas such as N₂
E) one must use a solid

Question 6

The internal energy of an ideal gas depends on:

A) the temperature only
B) the pressure only
C) the volume only
D) the temperature and pressure only
E) temperature, pressure, and volume

Question 7

The mean free path of air molecules at room temperature and atmospheric pressure is about:

A) 10^-3 m
B) 10^-5 m
C) 10^-7 m
D) 10^-9 m
E) 10^-11 m

Question 8

The mean free path of molecules in a gas is proportional to:

A) the molecular diameter
B) the reciprocal of the molecular diameter
C) the molecular concentration
D) the reciprocal of the molecular concentration
E) the average molecular speed

Question 9

A certain ideal gas has a temperature 300 K and a pressure 5.0 x10⁴ Pa.The molecules have a mean free path of 4.0 x10^-7m.If the temperature is raised to 350 K and the pressure is reduced to 1.0 x 10⁴ Pa the mean free path is them:

A) 6.9 x 10^-8m
B) 9.3 x10^-8m
C) 3.3 x10^-7m
D) 1.7 x10^-6m
E) 2.3 x10^-6m

Question 10

Evidence that molecules of a gas are in constant motion is:

A) winds exert pressure
B) two gases interdiffuse quickly
C) warm air rises
D) energy as heat is needed to vaporize a liquid
E) gases are easily compressed

Question 11

The mass of an oxygen molecule is 16 times that of a hydrogen molecule. At room temperature, the ratio of the rms speed of an oxygen molecule to that of a hydrogen molecule is:

A) 16
B) 4
C) 1
D) 1/4
E) 1/16

Question 12

Five molecules have speeds of 2.8, 3.2, 5.8, 7.3, and 7.4 m/s. Their root-mean-square speed is closest to:

A) 5.3 m/s
B) 5.7 m/s
C) 7.3 m/s
D) 28 m/s
E) 32 m/s

Question 13

In a system of N gas molecules, the individual speeds are v₁, v₂, ..., v_N. The rms speed of these molecules is:

A)
B)
C)
D)
E)

Question 14

The Maxwellian speed distribution provides a direct explanation of:

A) thermal expansion
B) the ideal gas law
C) heat
D) evaporation
E) boiling

Question 15

According to the Maxwellian speed distribution, as the temperature increases the average speed:

A) increases
B) decreases
C) increases at high temperatures and decreases at low
D) decreases at high temperatures and increases at low
E) stays the same

Question 16

As the pressure in an ideal gas is increased isothermally the average molecular speed:

A) increases
B) decreases
C) increases at high temperature, decreases at low
D) decreases at high temperature, increases at low
E) stays the same

Question 17

As the volume of an ideal gas is increased at constant pressure the average molecular speed:

A) increases
B) decreases
C) increases at high temperature, decreases at low
D) decreases at high temperature, increases at low
E) stays the same

Question 18

An ideal gas of N diatomic molecules has temperature T. If the number of molecules is doubled without changing the temperature, the internal energy increases by:

A) 0
B) 1/2NkT
C) 3/2NkT
D) 5/2NkT
E) 3NkT

Question 19

The difference between the molar specific heat at constant pressure and the molar specific heat at constant volume for an ideal gas is:

A) the Boltzmann constant k
B) the universal gas constant R
C) the Avogadro number N_A
D) kT
E) RT

Question 20

An ideal monatomic gas has a molar specific heat C_v at constant volume of:

A) R
B) 3R/2
C) 5R/2
D) 7R/2
E) 9R/2

Question 21

The specific heat C_v at constant volume of a monatomic gas at low pressure is proportional to Tⁿ where the exponent n is:

A) -1
B) 0
C) 1
D) 1/2
E) 2

Question 22

The ratio of the specific heat of a gas at constant volume to its specific heat at constant pressure is:

A) 1
B) less than 1
C) more than 1
D) has units of pressure/volume
E) has units of volume/pressure

Question 23

The ratio of the specific heat of an ideal gas at constant volume to its specific heat at constant pressure is:

A) R
B) 1/R
C) dependent on the temperature
D) dependent on the pressure
E) different for monatomic, diatomic, and polyatomic gases

Question 24

Both the pressure and volume of an ideal gas of diatomic molecules are doubled. The ratio of the new internal energy to the old both measured relative to the internal energy at 0 K is:

A) 1/4
B) 1/2
C) 1
D) 2
E) 4

Question 25

The pressure of an ideal gas of diatomic molecules is doubled by halving the volume. The ratio of the new internal energy to the old, both measured relative to the internal energy at 0 K, is:

A) 1/4
B) 1/2
C) 1
D) 2
E) 4

Question 26

The number of degrees of freedom of a rigid diatomic molecule is:

A) 2
B) 3
C) 4
D) 5
E) 6

Question 27

The number of degrees of freedom of a triatomic molecule is:

A) 1
B) 3
C) 6
D) 8
E) 9

Question 28

An ideal diatomic gas has a molar specific heat at constant pressure, C_p, of:

A) R
B) 3R/2
C) 5R/2
D) 7R/2
E) 9R/2

Question 29

When work W is done on an ideal gas of N diatomic molecules in thermal isolation the temperature increases by:

A) W/2Nk
B) W/3Nk
C) 2W/3Nk
D) 2W/5Nk
E) W/Nk

Question 30

When work W is done on an ideal gas of diatomic molecules in thermal isolation the increase in the total rotational energy of the molecules is:

A) 0
B) W/3
C) 2W/3
D) 2W/5
E) W

Question 31

When work W is done on an ideal gas of diatomic molecules in thermal isolation the increase in the total translational kinetic energy of the molecules is:

A) 0
B) 2W/3
C) 2W/5
D) 3W/5
E) W

Question 32

The heat capacity at constant volume of an ideal gas depends on:

A) the temperature
B) the pressure
C) the volume
D) the number of molecules
E) none of the above