Gas pressure: The force per unit area exerted by gas particles colliding with container walls. Units: Pascals (Pa) or N/m².
Absolute zero (0 K): The theoretical minimum temperature (−273°C) at which particles have minimum kinetic energy and gas pressure would be zero. Examined by Edexcel (14.14) and Eduqas only — it is not in the AQA, OCR A or OCR B specifications.
Kelvin (K): The SI unit of absolute temperature. T(K) = T(°C) + 273. Edexcel requires you to convert between the Kelvin and Celsius scales (14.15) but never uses Kelvin inside a gas calculation; Eduqas (Higher, Physics only) does use it in gas-law calculations. AQA, OCR A and OCR B do not examine the Kelvin scale in this topic.
Atmospheric pressure: The pressure exerted by the atmosphere on objects at Earth's surface, approximately 100,000 Pa (100 kPa). Decreases with altitude as there is less air above.
This definitions covers Key Definitions 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 5 of 11 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
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.