Practice Model of Water - 3.3.1 Particle Motion in Gases (GCSE Physics AQA)

Particle Motion in Gases

Movement of Particles

• Particles in a gas move constantly and rapidly. In a gas, particles are moving constantly. They move around each other randomly, at different speeds and different directions.

• Particles in a gas have high kinetic energy. The moving particles in a gas have kinetic energy. This kinetic energy is allowing the particles to move, but it is affected by the temperature of the particles.
• High temperature leads to high KE. As the temperature increases, the kinetic energy of the particles will also increase. The increase in kinetic energy is averaged across all the particles.

Movement related to Pressure

• Gas particles constantly collide. The particles in the gas will move around in different speeds and directions, and they will have lots of collisions. These gas particles are inside a container. The collisions will occur between two particles, or between a particle and the walls of the container.
• Colliding particles exert a pressure on the walls of a container. As the particles collide with the sides of the container, they will exert forces onto the walls of the container. All the individual forces from each collision will combine together. This combined force will exert a pressure on the walls of the container (since pressure exerted over an area will result in a force).

Effect of Temperature on Pressure

Increased temperature leads to an increase in pressure at a constant volume. The mechanism for this is shown in the flow chat below: