This topic summary covers Knowledge Organiser: Gas Pressure and Temperature within Gas Pressure & Temperature for GCSE Physics. Revise Gas Pressure & Temperature in Particle Model for GCSE Physics with 19 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 12 of 12 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Knowledge Organiser: Gas Pressure and Temperature
Key Terms
- Gas pressure: force per area from particle-wall collisions
- Absolute zero: 0 K = −273°C, minimum kinetic energy
- Kelvin: absolute temperature scale, T(K) = T(°C) + 273
- Upthrust: upward fluid force = weight of fluid displaced
Key Facts
- Pressure caused by particle-wall collisions
- Higher T → faster particles → more frequent + harder collisions → higher pressure
- Pressure ∝ absolute temperature (Kelvin) at constant volume
- Pressure in liquids increases with depth: P = ρgh
Key Equations
- p = F/A (Pa = N/m²)
- T(K) = T(°C) + 273
- p₁/T₁ = p₂/T₂ (constant volume)
- p₁V₁ = p₂V₂ (constant temperature)
- P = ρgh (pressure in liquid)
Exam Tips
- Particle explanation: speed + frequency + force of collisions
- ALWAYS convert to Kelvin for calculations
- Absolute zero: particles at minimum KE, p = 0 theoretically
- Don't confuse pressure increase with particles getting bigger
Common Mistakes
- Using Celsius instead of Kelvin: All gas law calculations must use temperature in Kelvin — convert by adding 273 to the Celsius value (0°C = 273 K)
- Incomplete particle explanation for pressure increase: Must state that particles move faster, collide more frequently with the walls, AND each collision exerts a greater force — all three points are needed
- Confusing pressure and volume changes: At constant temperature, increasing volume decreases pressure (p₁V₁ = p₂V₂); at constant volume, increasing temperature increases pressure
- Saying absolute zero means no energy: At absolute zero (−273°C / 0 K), particles have minimum kinetic energy — they do not stop completely in the classical model
- Forgetting units for pressure: Pressure must be in Pascals (Pa) and volume in m³ for the standard gas equations — check units carefully before substituting
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.
Quick recall flashcards
What is pressure?
Force per unit area (force divided by area)
Pressure equation
p = F/A