Thermodynamic study of monovalent and divalent cations in mixed solvent system by conductance method

Abstract

The ionic conductivities of potassium chloride (KCl) and calcium chloride (CaCl2) solutions in aqueous ethanol (0 to 50% mixtures) were measured at various concentrations (0.50 × 10−3 to 50 × 10−3 M) and at different temperatures (25 to 45°C) respectively. The viscosities of v/v aqueous ethanol compositions (0 to 50%) at different temperatures (25 to 45°C) were also measured. The conductivity data have been analyzed by various equations to evaluate molar conductivity at infinite dilution (), degree of dissociation (α), dissociation constant (K d), Walden constant, and energy of activation (E a). The values of ion--ion interactions (A) and ion--solvent interactions (B) have been calculated by the Debye--Huckel relation. The increase in value of B with rising temperature led to conclusion that potassium chloride (KCl) and calcium chloride (CaCl2) behave as structure breaker in aqueous ethanol mixtures. The thermodynamic parameters such as free energy change of activation (ΔG #), enthalpy change of activation (ΔH #) and entropy change of activation (ΔS #) have also been calculated.