Temperature & Pressure (Cambridge International IGCSE Science)

Temperature & energy of particles

• As the temperature of a gas increases, so does the average speed of particles in the gas

  • At higher temperatures, the particles have more kinetic energy

• The amount of pressure that a gas exerts on its container is dependent on the temperature of the gas

  • This is because particles gain kinetic energy as their temperature increases

Pressure & force of particles in a gas

Extended Tier Only

• Gases fill their container
• The pressure is defined as the force per unit area

$p=\frac{F}{A}$

• Where:

  • $p$ = pressure in pascals Pa
  • $F$ = force in newtons N
  • $A$ = area in metres-squared m²

• This equation and the particle model can be used to explain how particles exert pressure

• As the gas particles move about randomly they collide with the walls of their containers

• These collisions produce force at right angles to the wall of the gas container (or any surface)

  • Pressure is force per unit area, so the force of these collisions exerts a pressure

Gas molecules bouncing off the walls of a container exert a force perpendicular to the surface