GCSE Physics (AQA)

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Gas Volume & Pressure

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Particle model of matter Particle model and pressure

Gas Volume & Pressure

5:20 Gas Pressure and Kinetic Theory
Spec 4.3.3.2
Previous Demonstrating Gas Pressure Next Calculating Gas Volume & Pressure
  • It is possible to change the pressure and volume of a gas without affecting its temperature using a gas column.
  • The bottom of the column is filled with oil to trap air above it.
  • Volume of gas can be altered by pumping more oil into the column, compressing the air and decreasing its volume.
  • This method allows for the study of how air pressure changes without affecting temperature.
  • The relationship between gas volume and pressure is explained by the behavior of gas molecules:
  • Decreasing volume leads to shorter travel distances for gas particles, increasing collision frequency with container walls.
  • More collisions result in higher pressure as pressure is calculated by the sum of forces from these collisions.
  • A smaller volume also means a smaller surface area, concentrating the forces over a lesser area and thus increasing pressure.
  • If volume increases, the pressure decreases due to fewer collisions and forces being spread over a larger area.
  • This relationship can be observed and confirmed by measuring changes in gas volume at constant temperature using a pressure gauge and measuring the column length occupied by the air.
  • The findings can be plotted on a graph to illustrate the inverse relationship between pressure and volume, important for understanding gas behavior in scientific and educational contexts.

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