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

Partial molar volumes at infinite dilution, V2infinity, are reported f or some 1 : 1 electrolytes in dimethylformamide (DMF)-water mixtures c overing the whole fraction range at 298.15 K. The results obtained sho w that the behaviour of V2infinity both for alkali-metal halides and f or hydrophobic electrolytes is dependent on the added DMF. In the wate r-rich region, the alkali-metal halides exhibit small variations of V2 infinity, but two extrema, a minimum and a maximum, in the case of the hydrophobic electrolytes, are observed. In the DMF-rich region, a dra stic decrease of V2infinity for all electrolytes is exhibited. The res ults are discussed on the basis of ion-solvent and solvent-solvent int eractions.