All courses › Thermodynamics › Ideal gas law

Ideal gas law

The ideal gas law links pressure, volume, temperature and the amount of gas for an ideal gas. It is used to find one state property when the others are known, and holds equally well before and after a process, as long as the temperature is always in kelvin.

pV = nRT

ideal gas law,

R = 8.314

J/(mol·K)

T[\mathrm{K}] = t[^\circ\mathrm{C}] + 273.15

temperature conversion

Symbols

$p$	pressure	Pa
$V$	volume	m³
$n$	amount of substance	mol
$T$	temperature	K

Example

10 L of gas has $p = 200$ kPa and $T = 300$ K. The amount is $n = \dfrac{pV}{RT} = \dfrac{200.000\cdot 0.010}{8.314\cdot 300} \approx 0.802$ mol.

Always use kelvin in the ideal gas law, and convert pressure and volume to Pa and m³ when using

R = 8.314

J/(mol·K).

Practise basic concepts for free →

State properties and processes →

Part of Thermodynamics: Basic concepts.