ABSTRACT
The total energy of a gas is equal to the sum of its kinetic energy KE plus its potential energy PE. The PE of a gas is energy due to molecular forces of interaction between the molecules; these forces fall off very quickly as the distance of separation between the molecules increases, and usually can be ignored at separation distances greater than about 100 molecular diameters. Under these conditions, the total energy of the gas then becomes equal to its kinetic energy. An ideal gas is one which, by definition, has no interactive forces between its particles; furthermore, the particles of an ideal gas are point particles, which means they occupy no volume. Thus the total energy of an ideal gas is just equal to its KE.
