Solvent selectivity for the solvent-solute-water systems is decided most simply by the ratios of the mole fraction of the solute dissolved in the solvent-rich layer to the mole fraction of the solute dissolved in the water-rich layer.
The ability to predict these ratios would be of great value in selecting a potential solvent for a separation process. The volume changes of mixing for solute-solvent and solute-water systems were determined by pycnometric technique over the entire range of compositions except for 2-butanone （methylethylketone）-water and also were measured at 25 ℃ under atmospheric pressure for the following eight binaries : acetone-water, acetone-n-heptane, acetone-monochlorobenzene, acetone-1, 1, 2-trichloroethane, 2-butanone-water, 2-butanone-n-heptane, 2-butanone-monochlorobenzene and 2-butanone-1, 1, 2-trichloroethane.
Partial molal volume changes of mixing at infinite dilution of ketone to solvent were calculated from the above data. These values were compared with partial molal heat of mixing and distribution coefficients at infinite dilution which had aleady been reported for the same systems and the previously published distribution coefficients were correlated qualitatively with the trends of these values interpreted from a view-point of the intermolecular attraction forces which arised from the hydrogen bonding based on Ewell's theory. The solvents having the greater contraction of volume changes of mixing at infinite dilution were found to be more efficient as extracting agents.