The physics of osmotic pressure

Abstract

The proper application of the virial theorem to the origin of osmotic pressure provides a simple, vivid and complete explanation of the physical processes involved; osmosis is driven by differential solvent pressures. This simple and intuitive notion is widely disregarded, but the virial theorem allows an exact formulation and unifies a number of different treatments. It is closely related to a kinetic treatment devised by Ehrenfest over 100 years ago.

11 pages, 2 figures. The revised version is expanded and polished. In particular it places the core material in context and makes explicit its relation to classic kinetic treatments of osmosis