16IB Gas Laws
1. [1 mark]
A thin-walled cylinder of weight W, open at both ends, rests on a flat surface. The cylinder has a height
L, an average radius R and a thickness x where R is much greater than x.
What is the pressure exerted by the cylinder walls on the flat surface?
A.
B.
C.
D.
2. [1 mark]
A fixed mass of an ideal gas in a closed container with a movable piston initially occupies a volume V.
The position of the piston is changed, so that the mean kinetic energy of the particles in the gas is
doubled and the pressure remains constant.
What is the new volume of the gas?
A.
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B.
C. 2V
D. 4V
3. [1 mark]
A sealed container contains a mixture of oxygen and nitrogen gas.
The ratio
is
.
The ratio
is
A. 1.
B.
.
C.
.
D. dependent on the concentration of each gas.
4. [1 mark]
An ideal gas has a volume of 15 ml, a temperature of 20 °C and a pressure of 100 kPa. The volume of the
gas is reduced to 5 ml and the temperature is raised to 40 °C. What is the new pressure of the gas?
A. 600 kPa
B. 320 kPa
C. 200 kPa
D. 35 kPa
5. [1 mark]
An ideal gas of N molecules is maintained at a constant pressure p. The graph shows how the volume V
of the gas varies with absolute temperature T.
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What is the gradient of the graph?
A.
B.
C.
D.
6. [1 mark]
The pressure of a fixed mass of an ideal gas in a container is decreased at constant temperature. For the
molecules of the gas there will be a decrease in
A. the mean square speed.
B. the number striking the container walls every second.
C. the force between them.
D. their diameter.
7. [5 marks]
0.46 mole of an ideal monatomic gas is trapped in a cylinder. The gas has a volume of 21 m3 and a
pressure of 1.4 Pa.
(i) State how the internal energy of an ideal gas differs from that of a real gas.
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(ii) Determine, in kelvin, the temperature of the gas in the cylinder.
(iii) The kinetic theory of ideal gases is one example of a scientific model. Identify two reasons why
scientists find such models useful.
8. [1 mark]
Which of the following is not an assumption of the kinetic model of ideal gases?
A. All particles in the gas have the same mass.
B. All particles in the gas have the same speed.
C. The duration of collisions between particles is very short.
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D. Collisions with the walls of the container are elastic.
9. [1 mark]
Under what conditions of density and pressure is a real gas best described by the equation of state for
an ideal gas?
A. Low density and low pressure
B. Low density and high pressure
C. High density and low pressure
D. High density and high pressure
10. [1 mark]
An ideal gas and a solid of the same substance are at the same temperature. The average kinetic energy
of the gas molecules is
and the average kinetic energy of the solid molecules is
comparison between
A.
is less than
B.
equals
C.
is greater than
and
. What is the
?
.
.
.
D. The relationship between
and
cannot be determined.
11. [1 mark]
In the kinetic model of an ideal gas, which of the following is not assumed?
A. The molecules collide elastically.
B. The kinetic energy of a given molecule is constant.
C. The time taken for a molecular collision is much less than the time between collisions.
D. The intermolecular potential energy of the molecules is zero.
12. [1 mark]
What is the definition of the mole?
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A. The amount of substance that has the same mass as 6.02
1023 atoms of carbon-12.
B. The amount of substance that contains as many nuclei as the number of nuclei in 12 g of carbon-12.
C. The amount of substance that has the same mass as one atom of carbon-12.
D. The amount of substance that contains as many elementary entities as the number of atoms in 12 g
of carbon-12.
13. [1 mark]
A fixed mass of an ideal gas has a constant volume. Two quantities, R and S, of the gas vary as shown by
the graph below.
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What quantities do R and S represent?
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14. [1 mark]
What are the conditions of temperature and pressure at which the behaviour of a real gas approximates
to the behaviour of an ideal gas?
A. Low pressure and low temperature
B. Low pressure and high temperature
C. High pressure and low temperature
D. High pressure and high temperature
15a. [2 marks]
This question is about an ideal gas.
Describe how the ideal gas constant R is defined.
15b. [1 mark]
Calculate the temperature of 0.100 mol of an ideal gas kept in a cylinder of volume 1.40×10–3 m3 at a
pressure of 2.32×105 Pa.
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15c. [2 marks]
The gas in (b) is kept in the cylinder by a freely moving piston. The gas is now heated at constant
pressure until the volume occupied by the gas is 3.60×10–3 m3. The increase in internal energy of the
gas is 760 J. Determine the thermal energy given to the gas.
15d. [2 marks]
After heating, the gas is compressed rapidly to its original volume in (b). Outline why this compression
approximates to an adiabatic change of state of the gas.
16a. [3 marks]
This question is about internal energy and thermal energy (heat).
Distinguish between internal energy and thermal energy.
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16b. [2 marks]
Describe, with reference to the energy of the molecules, the difference in internal energy of a piece of
iron and the internal energy of an ideal gas.
16c. [4 marks]
A piece of iron is placed in a kiln until it reaches the temperature θ of the kiln. The iron is then quickly
transferred to water held in a thermally insulated container. The water is stirred until it reaches a
steady temperature. The following data are available.
Thermal capacity of the piece of iron = 60JK–1
Thermal capacity of the water = 2.0×103JK–1
Initial temperature of the water = 16°C
Final temperature of the water = 45°C
The thermal capacity of the container and insulation is negligible.
(i) State an expression, in terms of θ and the above data, for the energy transfer of the iron in cooling
from the temperature of the kiln to the final temperature of the water.
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(ii) Calculate the increase in internal energy of the water as the iron cools in the water.
(iii) Use your answers to (c)(i) and (c)(ii) to determine θ.
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