It has been observed that when the experiments are performed at relatively low pressure and temperatures, most of the real gases obey Boyle’s law and Charles’s law appreciably. However, behavior of real gases deviates considerably at elevated pressures and low temperatures. The ideal gas equation can be derived analytically using kinetic theory of gases with the assumptions.

i) A finite volume of gas contains large number of molecules.

ii) The size of the molecules is much smaller than average distance between the molecules. Therefore, they do not interact with each other or with the walls of the container except during collision.

iii) The collision between the molecules or their collision with the walls is perfectly elastic.

iv) The time duration of collision is negligibly small in comparison to time duration between two successive collisions of a molecule.

As long as these assumption are valid, the behavior of a real gas approaches nearly that of ideal gas.