Comparative conductimetric studies of salicylic acid in methanol-water mixtures at 25 °C

Conductivity data of salicylic acid in methanol-water mixtures were measured at 25 degrees C. The data were analyzed in two methods, the Hsia-Fuoss's and Fuoss 78's conductance equations and a comparison was made. The two methods concern the derivation of thermodynamic association constants and limiting molar conductivities for all solvent compositions. The limiting equivalent conductance decreases with the increase of methanol content in the binary mixtures over the whole range of the solvent composition, but the variation does not give a constant value of Walden product. The electrolytes were found to be practically completely associated in all studied solvent mixtures. The association constant of acid decreases with the increase in relative permittivity of the mixtures. The values of ionic coefficients of self diffusion and the ionic conductance at infinite solutions were estimated. (C) 2013 Production and hosting by Elsevier B.V. on behalf of King Saud University.