ideal gas

An ideal gas, also known as a perfect gas, is a theoretical concept of a gas which would obey the gas laws (i.e., PV = nRT) exactly. Such a gas would consist of perfectly elastic molecules, the volume occupied by the actual molecules, and the forces of attraction between them, being zero or negligible.


In practice, no gas shows ideal behavior, although, helium, hydrogen, and nitrogen approximate to ideality at high temperatures and low pressures.


See also ideal gas law and kinetic theory of gases.