Ionic association and thermodynamic parameters for solvation of vanadyl sulfate in ethanol-water mixtures at different temperatures

Conductance measurements of vanadyl sulfate have happened in binary mixed solvent with alcohol mass fraction 0%, 30% and 50% (W/W) (EtOH-H2O) at different temperatures from 298.15 to 313.15 K (with a step of 5 K). The experimental data have been analyzed by using the Fuoss-Hsia-Fernández-Prini (FHFP) equation. Molar conductance (Λm), limiting molar conductance (Λ0), Walden product (Λ0 η0), ion-pair association constant (KA), the activation energy for the transport process (Ea) and the standard thermodynamic parameters for association (∆ G°A, ∆ H°A and ∆ S°A) were estimated and discussed. The effect of formation hydrogen bond in solution also has been studied. The obtained results show that the association constant was increased as the relative permittivity of the solvent decreased while the molar conductance and the limiting molar conductance values were decreased. Furthermore, as the temperature increased, the association constant values were increased indicating the association process is endothermic.