An Ideal Gas Indeed Does Work in Expansion into Vacuum

Abstract

Basic thermodynamics is able to treat an actual (non-equilibrium) process as well as the corresponding equilibrium process. An example of such a pair of processes is familiar to every chemical engineer; namely, (Joule) free expansion of a gas and the corresponding equilibrium expansion [1]. Formerly, we thought that an ideal gas does no work in expansion into vacuum. It is shown that such a gas does work. This result is confirmed by experiments.