Preferential solvation of some copper (I), silver (I) and sodium (I) salts in acetonitrile plus n-butyronitrile and acetonitrlle plus N,N-dimethylacetamide mixtures

Viscosities and densities of Bu4NBPh4, Bu4NClO4, Bu4NI, Bu4NBr, Pr4NBr, Et4NI, Et4NBPh4, CuClO4,NaClO4 and NaBPh4 in AN+n-BTN and those of Bu4NBPh4, Bu4NClO4, Bu4NCF3COO, AgCF3COO and CuClO4 in AN+DMA mixtures in the concentration range (3-580)x 10(-4) mol dm(-3) containing 100, 80, 60, 40, 20 and 0 mol% AN have been measured at 298 K. The viscosity data have been analyzed using the Jones-Dole equation in the form: eta/eta(o) 1 +AC(1/2) + BC for unassociated and in the form eta/eta(o) = 1 + A (C alpha)(1/2) + B(C alpha) + B'(1-alpha) C for associated electrolytes. The A-coefficients of the Jones-Dole equation are positive and are in reasonably good agreement with the limiting theoretical values (A(eta)) calculated using Falkenhagen-Vernon equation in some cases and two to three times larger in other cases. The B coefficients of the electrolytes are positive and large in all cases. The ionic B+ and B- coefficients have been evaluated from the B- coefficients of the electrolytes using a method reported by Gill and Sharma. The derived results show a strong preferential solvation of Na+ and Cu+ by n-BTN in AN + n-BTN and that of Ag+ and Cu+ by DMA in AN+DMA mixtures. Br-, I- and ClO4- show weak preferential solvation by the same solvents while CF3COO- shows no preferential solvation in AN+ DMA mixtures. (c) 2006 Elsevier B.V. All rights reserved.