An ideal gas is an idealized gas model. The kinetic theory assumes that
- An ideal gas consists of a large number of gas particles in random motion, undergoing elastic collisions with one another and the walls of the container.
- No forces act on the molecules except during elastic collisions of negligible duration.
- The volume of the gas particles is negligible compared to the volume of the gas.
At standard temperature and pressure, most real gases including nitrogen, oxygen, hydrogen, noble gases, and some heavier gases like carbon dioxide can be treated as ideal gases within reasonable tolerances. Generally, a gas behaves more like an ideal gas at higher temperature, lower pressure and larger volume (as these conditions help to validate assumptions 2 and 3).