Conductance study of ion solvation in acetonitrile-rich regions of benzene and ethanol

Abstract

Limiting molar conductance (Λ_o) and ion-association constant (K_A) of Bu₄NBPh₄, Bu₄NClO₄, BU₄NNO₃, AgNO₃ and CuClO₄have been reported in acetonitrile (AN)-rich regions of benzene and ethanol (EtOH) at 25^oC. The Λ_o values of the electrolytes have been resolved into the limiting molar ionic conductance, (λ_i^o) values on the basis of reference electrolyte (Bu₄NBPh₄) assumption suggested by Gill. The effective ionic radii (r_i) of Bu₄N⁺, Ph₄B¯, CiO4", NO₃¯, Ag⁺ and Cu⁺ ions have been calculated in these mixtures. An examination of rj values of these ions reveals that in both the solvent systems, Ag⁺ and Cu⁺ ions undergo specific ion-solvent interactions with AN. However, both benzene and EtOH are found to lie in the same range as regards to their solvation properties. Solvophobic solvation is observed in case of Bu₄N⁺ and Ph₄B-ions in AN-EtOH mixture, whereas no such effect is observed in AN - benzene mixture. NO₃¯ and CiO₄¯ both show no change in their r_i, value in AN-benzene mixture. NO₃¯ in AN-EtOH mixture however, is found to undergo very weak preferential solvation by EtOH.