The partial molar volumes of a number of monovalent salts and polar species were measured In a series of organic solvents. The solvents Included ethanol, methanol, Af-methylformamlde (NMF), propylene carbonate, sulfolane, acetonitrile, acetone, and 4-methyl-2-pentanone. The polar species were n -propyl bromide, n-propyl iodide, and n-propyl chloride. The monovalent salts that were examined Included LIBr, Lll, LIN03, Nal, KI, Rbl, CsBr, tetrabutylammonlum Iodide, tetrabutylammonlum bromide, and tetrabutylammonlum perchlorate. The major observation was that the solvent effect on the partial molar volumes was most pronounced for monovalent salts. The solvent effect on the partial molar volume of the neutral solute was very small. The largest solvent effects are seen for the small monovalent salts when comparing aprotlc and protlc solvents. The conclusion was that the nonlonlc solutes do not grossly change the structure of the solvent, but the Ionic solutes change the structure of the solvent significantly.

The conductance of LII, LiBr, and Nal In acetonitrile and of tetra-n-butylammonlum Iodide and tetra-n-butylammonlum bromide In acetone and In 4-methyl-2-pentanone were measured as a function of pressure. Data are reported at 25 °C over a concentration range of 0.0001-0.03 M and at pressures up to 2-3 kbar. Analysis of these data using Justice's modification of the Fuoss-Onsager equation yields values of the limiting conductance and the association constants as a function of pressure. Both the limiting conductance values and the association constants decrease with Increasing pressure, and from the latter values of the volume change on association are calculated.

The rate of the halide exchange reaction of n-propyl bromide with iodide ion was measured in a series of protic and polar aprotic solvents over a pressure range of ambient to 1500 bar, with a few data to pressures as high as 6000 bar. The rate was fastest, the activation volume the most positive, and the equilibrium constant lowest in the least polar aprotic solvent, 4-methyC2-pentanone, while protic solvents such as low molecular weight alcohols gave much slower rates, more negative activation volumes, and higher equilibrium constants. The partial molal volume of the transition state is calculated in various solvents and shows that the solvent interaction with the small halide ion dominates in determining the very large solvent effect on reactions of this type.

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