Edexcel IGCSE Physics 5.22 Pressure Volume Relationship Questions

Practise tracing how compression or expansion changes gas pressure, then read container dimensions before solving for the new pressure.

Exam points

Use p₁V₁ = p₂V₂ to calculate an unknown pressure or volume for a fixed gas at constant temperature.
Calculate a container’s new volume from diagram dimensions before substituting into p₁V₁ = p₂V₂.
Explain that halving gas volume at constant temperature doubles pressure as wall collisions become more frequent.
State that gas amount and temperature must remain constant before applying p₁V₁ = p₂V₂.
Express the calculated volume in standard form when requested.

[Maximum number: 4]

This question is about gas pressure.

The width of the container is slowly decreased so that the volume of the container is smaller than before.

Diagram 2 shows the width of the container before and after this change. All other dimensions of the container remain the same.

The initial volume of the gas is 130 cm^3.
The initial pressure of the gas is 100 kPa.
Calculate the pressure of the gas after the width of the container is decreased.
Assume the temperature of the gas remains constant.

pressure = ............ kPa

Marking points:
- evaluation of new volume
- substitution into $p_{1}V_{1}=p_{2}V_{2}$
- rearrangement
- evaluation of new pressure

Example:
$V_{2}=130\times\frac{5.0}{8.4}=77\ \mathrm{cm^{3}}$ $100\times130=p_{2}\times77$ $p_{2}=\frac{100\times130}{77}$ $p_{2}=170\ \mathrm{kPa}$

Accept:
- $V_{2}=77.38\ldots\ \mathrm{cm^{3}}$
- any value that rounds to $170\ \mathrm{kPa}$
- ECF different yet incorrect volume

Marking guidance:
- Deduct 1 mark for a power-of-ten error.

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Edexcel IGCSE Physics 5.22 Pressure Volume Relationship Questions question 1