# Boyle's law

Boyle's law states that pressure is inversely proportional to volume, for a fixed amount of gas at constant temperature.

Key Concepts

$$p\propto {1\over V}$$

• $$p$$ is pressure (Pa)
• $$V$$ is volume (m3)

$$p_1V_1=p_2V_2$$

Essentials

Simulated experiment

Boyle's law can be verified by measuring the pressure of a fixed mass of gas as its volume is changed. The graph of p vs V shows an inverse relationship.

Kinetic theory explanation

The pressure of a gas increases when the volume is made smaller. This is because the molecules are closer to the walls and so collide with the walls more often. If the temperature is constant, so is the kinetic energy of the molecules and the force exerted by each collision.

Test Yourself

Use quizzes to practise application of theory.

Exam-style Questions