The Expansion of Gases

Abstract

An expanding gas, as we have noted in considering specific heats, exerts a force against its surroundings, its expanding container, and so does work. The energy to do that work comes from the energy of random motion of the molecules. If this energy is replaced as fast as it is removed, by a flow of heat into the gas, the temperature can be maintained constant. If, on the other hand, there is no flow of heat energy into the gas, the average energy per degree of freedom will be reduced, that is, the temperature of the gas will drop.