Gas Laws

What is Gas Laws?

Within Physics, which covers forces, energy, waves, electricity, magnetism, light and space explained through motion and experiments, this topic explains Gas Laws. Physics topics explain how things move, push, heat up and carry energy, so each one here pairs a definition with a live model you can change.

Check that you can explain Gas Laws in your own words and give one example from everyday life. If you can do that, you have understood the core idea.

Understanding Gas Laws explains how the physical world behaves, from sport and transport to electricity and medicine.

Gas Laws in detail

For a fixed mass of gas, Boyle's law states that pressure and volume are inversely proportional at constant temperature (pV = constant). Charles's law says volume is proportional to absolute temperature at constant pressure, and the pressure law says pressure is proportional to absolute temperature at constant volume.

Temperatures must be in kelvin. Combined, these give pV/T = constant, or the ideal gas equation pV = nRT. Particle explanations link them to collisions: squeezing a gas increases collision frequency, and heating increases particle speed. These laws are used in tyres, syringes, balloons and engines.

How the interactive helps you understand Gas Laws

Watch the gas particle model in the interactive. Use any sliders or buttons it offers to change the values and see how the gas particle model responds.

Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Gas Laws.

Real-life uses and examples

• Explain everyday devices, such as brakes, lifts or chargers, using Gas Laws.
• Use Gas Laws to make sense of a practical and its results.
• Answer “explain” questions by linking Gas Laws to a clear cause and effect.

Common mistakes to avoid

• Forgetting that some quantities, such as force or velocity, also have a direction.
• Mixing up Gas Laws with a related quantity that has different units.
• Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.