Gas pressure

• Temperature of gas is related to the average kinetic energy of particles in the gas.
• Higher temperature = Higher average kinetic energy of particles in a gas
• Gas pressure is caused by gas particles colliding with a surface and exerting a net force on it
• How gas pressure is effected by temperature at a constant volume :

  • Temperature increases of gas,
  • This gives molecules more kinetic energy
  • This causes more frequent collisions
  • Therefore, pressure increases
• How gas pressure is effected by volume at a constant temperature :

  • Volume increases
  • This means that particles become more spread out
  • Therefore, less collisions
  • Meaning, pressure decreases
• Doing work on gases:

  1. Force is applied to gas, work is done as energy is transferred
  2. Doing work increases its internal energy
  3. Temperature of gas increases
• Boyle's Law

  For a fixed mass of gas at a constant temperature, the pressure is inversely proportional to the volume, as the volume decreases the pressure increases
• constant = pV 


  p- pressure (Pascals,P or N/m^2)

  V- volume (m^3)
• P1 V1 = P2 V2 (Boyle's Law)

  Pressure x Volume of gas one is the same as, Pressure x Volume of gas two.
• P1 V1 = P2 V2 : Example

  P1= 100,000 Pa

  V1= 0.0001 m^3

  P2= 50,000 Pa

  V2= ?

  100,000 x 0.0001 /50,000 =V2 = 0.0002m^3