The translational diffusion coefficients are reported for polystyrenes with molecular weights 2000, 4000, and 9000 in cyclohexane at infinite dilution from 283.2 to 348.2 K. The results suggest that the hydrodynamic radii stay constant to within ±3% and that the real chain for molecular weight 9000 at 308.2 K is well represented by a Gaussian or Monte Carlo model involving the idea of statistical steps. Furthermore, the success of Hildebrand's free‐volume empiricism has led to a correlation between Dμ0/T and M which represents the observed diffusivities to within ±2%.

Binary diffusion coefficients at high dilution are measured for ethane and ethylene dissolved in cyclohexane at temperatures from 280.5 to 363.2 K and for benzene in cyclohexane and n-hexane up to their critical temperatures. With the effective hard-sphere diameters backed out from self-diffusion data from both solute and solvent molecules and fitted to Protopapas, Anderson, and Parlee’s formula, the prediction with the Sung–Stell theory is found to agree to within ±7% of experimental data for wide ranges of solute-to-solvent mass and size ratios at temperatures up to the critical point.

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