Stop 8 of 12 · The path
Gases — squeeze and heat
Gases fill everything. Pressure, volume, and temperature move together — warm it and it pushes harder.
Bench tool
Gas lab: squeeze it, heat it
Push the sliders and watch the piston answer:
How it works
- Boyle: squeeze twice as hard, volume halves (fixed T).
- Charles: heat it, it swells (fixed P).
- Together: PV = nRT. One equation ties pressure, volume, moles, temperature.
Worked examples
Bike pump warms. Squeezing air does work on it — temperature rises.
1 mol at room conditions ≈ 24 L. Handy estimate for any gas.
Balloon in sun. T up, V up — same air, bigger balloon.
Where it goes wrong
Kelvin for gas maths. 0 °C is 273 K. Doubling °C does not double temperature — Kelvin does.
Try it at home: syringe squeeze
Feel Boyle's law. Seal a plastic syringe tip with your finger and gently push the plunger at room temperature. It pushes back harder the further you press — smaller volume, higher pressure.
For teachers
Learners blame volume changes on particles growing or shrinking — probe by asking what heating does to particle speed vs size. Quickest check: ask why a cold tyre reads low with the same air inside.