Ionic association and solvation study of CoSO4 in aqueous - organic solvents at different temperatures

Hydrogen bond formation effect, temperature and relative permittivity on the thermodynamic properties and the ion pair formation behavior was considered through the investigation of the specific conductance of CoSO4 in 30%, 20% and 10% (w/w) methanol- water (MeOH- H2O), and DMF-water (DMF-H2O) mixtures at various temperatures (25, 30, 35, and 40 °C). The conductivity data obtained have been analyzed using the Fuoss - Shedlovsky conductivity equation. Molar conductance (Λ), limiting molar conductance (Λ0), Walden product (Λ0η0), ion pair formation constants (KA), the activation energy of the transport process (Ea), hydrodynamic radii (RH), and standard thermodynamic parameters of association (ΔG°A, ΔH°A and ΔS°A) were calculated and discussed. The molar conductance that obtained from experimental work was reduced as the dielectric constant of the solvent reduced but, the ion pair formation constant increased. Moreover, the results show that as the temperature increased, the molar conductance and the association constant values were increased specify that the ion pair formation behavior is endothermic. The hydrogen bond creation was also affected on the ion pair formation of the considered salt.