Light scattering measurement and theoretical interpretation of mutual diffusion coefficients in binary liquid mixtures

Abstract

Mutual diffusion coefficients for eleven binary systems of simple organic liquids have been measured by laser light scattering. By separating the mutual diffusion coefficient into a kinetic diffusion coefficient and a thermodynamic factor, we have been able to analyze the dynamical information contained in the kinetic coefficient in terms of a simple hard sphere theory of molecular motion. The hard sphere model of the kinetic diffusion coefficient is shown to be accurate for ideal and moderately nonideal solutions, and for both spherical and very nonspherical molecules. Only for extremely nonideal solutions were we unable to interpret diffusion coefficient data by our methods of analysis.