LIMITING PARTIAL MOLAR VOLUMES OF ELECTROLYTES IN DIMETHYLFORMAMIDE-WATER MIXTURES AT 298.15-K

Partial molar volumes at infinite dilution, V2infinity, are reported for some 1 : 1 electrolytes in dimethylformamide (DMF)-water mixtures covering the whole fraction range at 298.15 K. The results obtained show that the behaviour of V2infinity both for alkali-metal halides and for hydrophobic electrolytes is dependent on the added DMF. In the water-rich region, the alkali-metal halides exhibit small variations of V2infinity, but two extrema, a minimum and a maximum, in the case of the hydrophobic electrolytes, are observed. In the DMF-rich region, a drastic decrease of V2infinity for all electrolytes is exhibited. The results are discussed on the basis of ion-solvent and solvent-solvent interactions.