The Eyring model of viscous flow in liqs. was extended to mixtures A relation was derived between the diffusion coefficient and the internal pressure of solvents (for infinitely diluted solns.) using a thermodn. method. The size of the hole required for diffusion equals the solute-mol. vol.; the diffusion activation energy depends on the solute-solvent interaction and on the creation of the hole.I

Key words: DIFFUSION COEFFICIENTS, ACTIVATION ENERGY, VISCOSITY, MOLECULAR MODEL, VISCOUS FLOW, VISCOSITY COEFFICIENT, INTRINSIC PRESSURE