CourseCourseConceptConceptDocumentDocument

CAIE A-Level Physics A2 15.2 Equation of State Questions

Practise distinguishing ideal-gas behaviour and applying pV = nRT or pV = NkT with consistent units, mole data or molecule data.

Syllabus
2028–2030
Course
Physics 9702
Level
A2

Exam points

  • identify ideal-gas behaviour and apply pV = nRT or pV = NkT to calculate state variables
  • use k = R/N_A and choose the appropriate mole or molecule form of the equation of state

Covered syllabus points

15.2.1—A gas obeying pV ∝ T, where T is the thermodynamic temperature, is known15.2.2—The equation of state for an ideal gas expressed as pV = nRT15.2.3—That the Boltzmann constant k is given by k = R / NA

Question 1

[Maximum number: 4]

Question (a)

(a)

State what is meant by an ideal gas.

[ 2 ]

Question (b)

(b)

A sample of 0.26 m30.26 \mathrm{~m}^{3} of an ideal gas is at pressure 2.0×105 Pa2.0 \times 10^{5} \mathrm{~Pa} and temperature 290 K .

Determine:

[ 2 ]

Question (i)

(i)

the number N of molecules of the gas

N =
[ 2 ]

Question 2

[Maximum number: 5]

Question (a)

(a)

An ideal gas has amount of substance n.

The gas is initially in state X , with pressure 2 p and volume V.
The gas is cooled at constant volume to state Y , with pressure p.
The gas is then heated at constant pressure to state Z , with volume 2 V .
Finally, the gas returns at constant temperature to state X .

[ 5 ]

Question (i)

(i)

Determine an expression for the temperature T of the gas in state X , in terms of n, p and V.
Identify any other symbols that you use.

[ 2 ]

Question (ii)

(ii)

On Fig. 4.1, sketch the variation with volume of pressure for the gas as the gas undergoes the three changes. The state X is labelled. Label states Y and Z .

Fig. 4.1

Fig. 4.1

[ 3 ]

Question 3

[Maximum number: 2]

State what is meant by an ideal gas.

All question bank results loaded