Diffusion in a Mixed Dense Fluid

Abstract

By using Thorne's extension of the Enskog theory for diffusion in a dense mixed hard‐sphere fluid, equations are developed expressing the mutual diffusion coefficient as a function of composition. Use is made in the derivation of the expression for the contact distribution function obtained by Lebowitz from the theory of Percus and Yevick. For molecules of the same size, the equations reduce to those of Longuet‐Higgins, Pople, and Valleau. Variation of the diffusion coefficient with density is discussed and the theory is applied to the diffusion of gases in liquids and to systems where either solute or solvent are dissimilar in size and mass. The Stokes–Einstein equation is also discussed.