A COMPARISON OF OSMOTIC AND ACTIVITY COEFFICIENTS OF SOME SOLUTES IN STRUCTURED SOLVENTS

Osmotic and activity coefficients have been calculated from freezing point depression measurements for fourteen solutes in ethylene carbonate and for five solutes in N-methylacetamide. These data are compared with those reported previously for some of the solutes in N-methylacetamide and with data for some of the same solutes in aqueous solutions. Reversals in the order of the coefficients of urea and 1,3-symmetrical dimethylurea and the shift in the position of the ammonium ion among the alkali metal ions in these systems gives an indication of the relative importance of solute-solvent interactions in the various solvents. Zinc chloride and zinc iodide are found to be un-ionized and perhaps polymeric in ethylene carbonate as a solvent.