What are the gas laws?

The gas laws: PV = nRT. A gas is a crowd of fast molecules hitting the walls. Squeeze it and the pressure rises, heat it and it swells or pushes harder, add more and it needs more room: all of this is one rule, PV = nRT.

Read how it works: What are the gas laws? · The history of the gas laws · More boxes on Glassbox

Chapters in this interactive model

1. Squeeze it, heat it, fill it: PV = nRT: One cylinder of air, four dials, and the rule that links them all.
2. Breathing and engines: Boyle’s law at work: Your chest grows and air rushes in. An engine squeezes air so fast it gets hot enough to light diesel.
3. Hot tyres and pressure cookers: Seal a gas in and heat it: the pressure climbs. That is Gay-Lussac’s law.
4. Hot air balloons and air fryers: Heat air and it swells, so each litre gets lighter. That is Charles’s law.
5. When gases stop being ideal: Squeeze CO₂ and it turns to liquid. An LPG cylinder breaks the rule on purpose. And heavy gases fill jars too.