Heats of Ionization of Water in Glycerol+ Water, t-butanol+ Water and Dioxane+ Water Mixtures and Comparison of the Thermodynamics of Ionization of Water in Different Mixed Solvents

Department of Applied Chemistry, Calcutta University, 92 Acharya P. C. Road, Calcutta-700 009

Department of Chemistry, Kalyani University, Kalyani, Nadia

Manuscript received 12 July 1978, accepted 3 October 1978

The heats of ionization for the reaction 2H₂O$\rightleftharpoons$ H₂O⁺+OH^- have been determined calorimetrically in several mixed solvents viz. t- butanol+ water, glycerol + water and dioxane + water mixtures. The data for the heats of ionization in methanol +water, ethanol+ water, etbyleneglycol +water and dimethyl sulphoxide+ water have been taken from the literature for comparison. The heats of ionization data have been coupled with appropriate free energy data where available to calculate the entropy changes in different solvent systems. A critical evaluation of the different factors affecting the thermodynamics of ionization in different mixed solvents have been made in terms of ion — solvent interactions and structural aspects. The limitations for the proper interpretation of the thermodynamics have been stressed.