Pressure - GCSE Chemistry Definition

In chemistry, pressure is the force that gas particles exert when they collide with the walls of a container. It tells us how strongly the gas is pressing on the surfaces around it.

Gas pressure can increase if:

• The number of gas particles increases (more collisions)

• The temperature increases (particles move faster and hit harder)

• The volume of the container decreases (particles collide more often)

Pressure is important in closed systems and chemical reactions involving gases, such as those where gas is collected or produced. It is usually measured in pascals (Pa) or atmospheres (atm).