EFFECT OF SOLVENT COMPOSITION ON IONIC MOBILITIES OF SOME TETRAALKYLAMMONIUM AND COMMON IONS IN PROPYLENE CARBONATE PLUS METHANOL MEDIA AT 25-DEGREES-C

Precise conductance measurements are reported for tetraalkylammonium b romides, R(4)NBr (R = methyl to heptyl), sodium tetraphenylborate (NaB Ph(4)) and tetrabutylammonium tetraphenylborate (Bu(4)NBPh(4)) in bina ry mixtures of propylene carbonate (PC) and methanol at four different mole fractions viz. 0.1, 0.2, 0.4 and 0.6 of PC. The conductance data have been analyzed by the 1978 Fuoss conductance equation in terms of the limiting molar conductance, Lambda(0), the Walden product, Lambda (0) eta(0), and the association constant, K-A. Single ion conductances have been determined using Bu(4)NBPh(4) as the ''reference electrolyt e''. The K-A values indicate the possibility of ionic association for these salts in this protic-dipolar aprotic solvent mixtures. Evaluatio n of Stokes radii shows that the tetraalkylammonium ions remain almost unsolvated over the whole composition range of the mixtures, whereas the Na+ ion is highly solvated at all percentages of the mixed solvent s, and the Br- ion shows solvational behaviour only at low PC content in the mixture.