Statistical Mechanical Theory of the Viscosity Coefficients of Binary Liquid Solutions

The method of the pair space linear relations is used to develop a formula for the coefficient of viscosity of a binary liquid solution from statistical mechanics. When the solution is regular a statistical-mechanical analog of the Stokes-Einstein equation is obtained in which the product of the self-diffusion coefficient and the viscosity is expressed as a composition independent average over the radial distribution function for unlike pairs. The relationship between the present theory and the results of experimental measurements of viscosity and diffusion coefficients is discussed at some length, and the Gordon equation for the mutual diffusion coefficient is derived.