Describe what is meant by the pressure of a gas, and explain how increasing the temperature of a gas at constant volume affects its pressure. Your answer should refer to the behaviour of gas particles.

Eduqas GCSE Physics — 2.6 Particle physics and using physics to investigate the universe · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Pressure is the perpendicular force per unit area exerted on the surfaces of a container by gas particle collisions.
Increasing the temperature raises the average kinetic energy of the gas particles, so they move faster.
Faster particles collide with the walls more often and with greater force.
The increased frequency and force of collisions raise the overall pressure.

Examiner tips

  • Use the definition of pressure (force/area) and link it to particle collisions.
  • Show the chain: higher T → higher KE → faster particles → more frequent and stronger collisions → higher pressure.
  • Keep the answer concise and use the exact wording from the mark scheme.

Common mistakes

  • Confusing pressure with density or volume.
  • Using vague terms like "more gas" instead of "more frequent collisions".
  • Not mentioning the force per unit area definition of pressure.

Mark scheme (4 marks)

  1. Pressure is the perpendicular force per unit area exerted on the surfaces of a container (due to gas particle collisions)
  2. Increasing temperature increases the average kinetic energy (and speed/velocity) of the gas particles
  3. Particles collide with the container walls more frequently
  4. Each collision exerts a greater force on the walls, so overall pressure increases

Key terms in this question

pressure of a gas · temperature

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