IONIC PARTIAL MOLAR VOLUMES IN NONAQUEOUS SOLVENTS

Standard partial molar volume data at 298 K for eight tetra-alkyl or -aryl ions and 13 smaller ions in ten solvents, including water, have been statistically related to diverse ion and solvent properties. The radius cubed is the primary ion property determining the volumes for both kinds of ions, as expected. Secondary effects are due to the polarizability of the large ions and the hydrogen bonding abilities of the smaller ones. The molar volumes of the solvents, modified by their polarizabilities as well as their solubility coefficients are the main solvent properties accounting for the ionic volumes. The effects of solvent compressibility are also explored, but the dipole moment and relative permittivity do not play a role.