Reformulation of Thermomolecular Pressure Effect toward Thermal Diffusion

Abstract

In many standard monographs of nonequilibrium thermodynamics, there are inconsistent parts of confusion in terminology as well as in notation, especially in the area of thermal diffusion, between quantities of transport and transported. Such a situation is corrected at an elementary level. As a result, the chemical potential of a diffusing species should be the “transported” Gibbs energy per mole. Based on this notion, the assumption of local equilibrium and the Gibbs equation can effectively and consistently be applied. Referring to a binary mixture, individual quantities of transport are discussed in harmony with “absolute” quantities introduced by de Groot and Mazur, in connection with the relative quantities of transport in common use.