Study on ion–solvent interactions of alkali metal salts in pure methanol and its binary mixtures with ethane-1,2-diol by a conductometric technique

Electrolytic conductivities of some sodium salts (NaI, NaSCN, CH3COONa) have been studied in 0, 25, 50 and 75 mass% ethane-1,2-diol + methyl alcohol mixtures at 293.15, 298.15 and 303.15 K. The limiting molar conductivity (Λ°), the association constant (KA) and the distance of closest approach of ion (R) have been evaluated using the Fuoss conductance equation (1978). The association constant (KA) decreases with temperature while it tends to decrease in the order: 0 mass% > 25 mass% > 50 mass% > 75 mass% ethane-1,2-diol + methyl alcohol mixtures. Thermodynamic parameters ΔH°, ΔG° and ΔS° along with the Walden products (Λ°η) are obtained and discussed. The results have been interpreted in terms of ion–solvent interactions and structural changes in the mixed solvents.