PROPERTIES OF ORGANIC-WATER MIXTURES .7. SELF-DIFFUSION COEFFICIENTS OF NA+ IN ETHYLENE GLYCOL-WATER AND GLYCEROL-WATER MIXTURES AT 25 DEGREES

Self-diffusion coefficients, script DNa, of Na+ were measured for water mixtures of ethylene glycol and of glycero l at 25° (ℳNaCl = 0.1) by the radiometric porous-frit method. The diffusion coefficients decrease more rapidly in glycerol than in glycol solutions, qualitatively, as expected from the viscosities of the systems. The diffusion-viscosity product, script Dη/η0, for the ethylene glycol system is essentially independent of solvent composition. In the glycerol system, however, script Dη/η0 rises in the organic-rich region. In contrast, script Dη/η0 for water mixtures of methanol, ethanol, and 1-propanol was earlier found to decrease in the same region. The self-diffusion-composition curves for the ethylene glycol and glycerol systems are similar to the corresponding NaCl limiting equivalent conductance-composition curves.