Ideal gas
A theoretical gas obeying the ideal gas equation pV = nRT, where p is pressure, V is volume, n is number of moles, R = 8.31 J/(mol·K) is the gas constant, and T is absolute temperature. Ideal gases have negligible intermolecular forces and particle volume compared to container volume. Real gases approach ideal behaviour at low pressures and high temperatures.
Formula
pV = nRT
Real World
Scuba divers use the ideal gas equation to calculate how volume of air in their tanks changes as pressure increases at depth — a 10 m descent roughly doubles surrounding pressure, halving the volume a given mass of air would occupy.
Exam Focus
Always convert temperature to Kelvin and pressure to Pascals before substituting into pV = nRT — using Celsius or kPa is one of the most common mark-losing errors.
How well did you know this?