Exam Focus

🎯 Exam Focus

Frequently Examined

Gas pressure is examined both as particle model explanations and as calculations. Examined in Edexcel 1PH0/2 (Paper 2). Edexcel includes pressure-volume-temperature relationships at Higher tier — the combined gas law (pV/T = constant) is explicitly tested in Edexcel 1PH0. Edexcel also uses context-based scenarios such as car tyres, aerosol cans, and syringes.

• "Explain using the particle model" (3-4 marks): Must include speed of particles, frequency of collisions, and force of collisions. All three points needed for full marks.
• Absolute zero explanation (2 marks): State temperature, state that particles have minimum kinetic energy / theoretically zero pressure.
• Kelvin conversion (1 mark): T(K) = T(°C) + 273. Straightforward mark if you remember the formula.
• Higher only — gas law calculations (3 marks): Edexcel 1PH0/2 tests p₁/T₁ = p₂/T₂ (constant volume), p₁V₁ = p₂V₂ (constant temperature), and the combined pV/T = constant. Always convert to Kelvin first.
• Pressure in liquids (2 marks): Explain why pressure increases with depth — more liquid above exerts greater weight/force.
• "Suggest" questions (Edexcel): Given a novel sealed container scenario, suggest what happens to pressure or volume when temperature changes — apply the correct gas law.