9701 · 4.1
The gaseous state: ideal and real gases and pV = nRT
Gases are mostly empty space with particles in constant, random motion. The ideal gas law is a simple but powerful equation that describes how a gas's pressure, volume, and temperature are all interconnected.
Need to know
What you need to know
- Gas particles are in continuous, random, straight-line motion.
- The volume of the gas particles is negligible compared to the volume of the container.
- There are no attractive or repulsive forces between gas particles.
- Collisions between particles and with the container walls are perfectly elastic (no kinetic energy is lost).
- The average kinetic energy of the gas particles is directly proportional to the absolute temperature (in Kelvin).
Explanation
The Rules of Gas Behaviour
- Ideal gas: particles far apart, random motion, elastic collisions.
- Boyle’s law: p ∝ 1/V at constant T (n fixed).
- Charles’s law: V ∝ T at constant p; Gay-Lussac: p ∝ T at constant V.
- Ideal gas equation: pV = nRT (R = 8.31 J mol⁻¹ K⁻¹).