Misconception 1: "Pressure increases because particles get bigger when heated"
Particles do not change size when heated. Pressure increases because the SAME particles move FASTER — they hit the walls more frequently and with more force. Size of particles is unchanged.
Misconception 2: "Pressure and temperature are linked using Celsius"
Eduqas only: in a gas-law calculation that involves temperature, the temperature must be in Kelvin (absolute), not Celsius — −273°C = 0 K, so always convert with T(K) = T(°C) + 273. On AQA, Edexcel, OCR A and OCR B the only gas-law calculation is p₁V₁ = p₂V₂ at constant temperature, which contains no temperature value at all, so no conversion ever arises.
Quick Check: A sealed gas canister is left in direct sunlight and warms up. Using the particle model, explain what happens to the pressure inside the canister.
The gas particles gain kinetic energy and move faster. This means they collide with the canister walls more frequently, and each collision exerts a greater force. Both effects increase the pressure inside the canister — this is why canisters carry warnings not to expose them to heat.
This common misconceptions covers Common Misconceptions within Gas Pressure & Temperature for GCSE Physics. Revise Gas Pressure & Temperature in Particle Model for GCSE Physics with 29 exam-style questions and 30 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 6 of 11 in this topic. Use this common misconceptions to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Gas Pressure & Temperature
A sealed gas container is heated. What happens to the pressure of the gas inside?
A sealed gas cylinder is heated. Explain, using particle theory, why the pressure of the gas increases when the temperature increases.