Causes and effects of gas pressure

• • Increasing the temperature of a gas transfers energy to the particles, which increases the kinetic energy of the particles
  • This increases the average speed of the particles
• • As gas particles move quickly, they collide with anything
  • When they collide with something, they exert a force and so a pressure
  • In a sealed container, colliding with the walls creates outward gas pressure due to the force exerted by the particles onto the walls
• • If the volume is kept constant, increasing the temperature will increase the speed and so the pressure
  • If the temperature is kept constant, increasing the volume decreases the pressure (more area, less collisions)
• • Pressure and volume are inversely proportional
  • When volume increases, pressure decreases
  • When volume decreases, pressure increases
• • Boyle's law: P1V1=P2V2
• • Pressure causes a force inside the container
  • There is also a force outside the container due to the pressure around it
  • Any change to the pressure will cause the container to compress or expand, due to the overall force
• HELIUM BALLOON EXAMPLE:

  • If a balloon is released, it rises
  • Atmospheric pressure decreases with height, so pressure outside the balloon decreases
  • This causes the balloon to expand until the pressure inside drops to the same at the atmospheric pressure
• • Transferring energy by applying a force is known as doing work
  • Doing work on a gas increases internal energy, which can increase temperature
• BIKE PUMP EXAMPLE:

  • Gas applies pressure to plunger of pump and so exerts a force on it
  • Work has to be done against this force to push down the plunger
  • This transfers energy to the kinetic stores of the gas particles, increasing the temperature