What does Boyle's law say?
Keep temperature fixed and squeeze a gas: its volume shrinks. Lower the pressure and it expands. Double the pressure and the volume halves—an inverse relationship written P₁V₁ = P₂V₂, which graphs as a hyperbola. In a smaller space, molecules hit the walls more often.
What are everyday examples?
Push the plunger of a sealed syringe and it gets harder. Chip bags puff up on planes and mountaintops. Scuba divers must never hold their breath while ascending, because the air in their lungs expands. Fix pressure instead and vary temperature, and you get Charles's law; combine them and you reach the ideal gas law, PV = nRT.
FAQ
- Does it hold if temperature changes?
- No—only at constant temperature.
- Do real gases follow it exactly?
- Not at high pressure or low temperature, where molecular size and attraction matter.
Sources reviewed: 2026-10-25
References
- Boyle, R. (1662). A Defence of the Doctrine Touching the Spring and Weight of the Air.
- Atkins, P., & de Paula, J. (2014). Atkins' Physical Chemistry (10th ed.). Oxford University Press.