Conductance study of ion solvation in DMSO, MeOH and DMSO-MeOH mixtures at25 degrees

Solvation behavior of Li+, Na+, K+, Ag+ and NO3- ions has been studied from the conductance measurement of solutions of LiNO3, NaNO3, KNO3, AgNO3 and Bu4NNO3 in DMSO-MeOH mixtures. The data have been analyzed in terms of limi ting molar conductivity (Lambda(o)) and ion-association constant (K-A) usin g a least-squares computer program of the Shedlovsky conductivity model. Th e limiting ionic molar conductivity (lambda(i)(o)) has been calculated on t he basis of Ph4PBPh4 assumption; lambda(o)(Ph4P+) congruent to lambda(o)(Ph 4B-) and effective ionic radii (r(i)) calculated using empirical modificati on of the Stokes' model. The r(i) results are compatible with K-A values. A n obviously typical difference in selective solvation for cations, Li+, Na, K+ and Ag+ is observed. Weak preferential solvation of NO3- by MeOH is re flected over the entire solvent composition range, which is found to be in contrast to the solvation of ClO4- in DMSO-MeOH mixtures.