The ideal gas law also expressed as a general gas equation can be considered as the equation of the state of a hypothetical ideal gas. It is used to examine the behaviour of gases in different conditions, but it has several limitations. The ideal gas law does not give any explanation on whether a gas heats or cools during the process of expansion or compression. Most of the ideal gases do not cause any change in temperature except for some of them. It was first derived in 1834 by Benoit Paul Emile Clapeyron.