Verification of the Onsager Reciprocal Relations in a Molten Silicate Solution

A key hypothesis in the generalized theory of nonequilibrium thermodynamics is the principle of microscopic time invariance as enunciated by Onsager in the 1930s. At the macroscopic level, Onsager's hypothesis is represented by a set of relations known as the Onsager reciprocal relations, which, when applied to isothermal, multicomponent diffusion, demand the symmetry of the phenomenological matrix that connects mass fluxes to chemical potential gradients. On the basis of experimentally determined diffusion coefficients and thermochemical data for the molten system CaO-Al(2)O(3)-SiO(2), the Onsager phenomenological coefficients have been computed, including an analysis of error. Within experimental uncertainty, the Onsager matrix is indeed symmetric.