Chapter summary
The Gaseous State, at a glance
Know when the ideal-gas model works, calculate gas quantities and separate the pressures in a mixture.
A-Level 9476 (2026-2027)
Quick revision
Revisit the essentials, then return to an explanation when you need it.
| Situation | Relationship or decision |
|---|---|
| Single ideal gas | pV = nRT; kelvin temperature is essential. |
| Molar mass | M = mRT/pV. |
| Mixture | pi = xi ptotal; use mole fractions. |
| Collected over water | Subtract water-vapour pressure before calculating dry-gas amount. |
| Most nearly ideal | Low pressure, high temperature. |
| Deviation | Attractions and finite particle volume can have different effects. |