THERMODYNAMIC STUDIES OF HYDROGEN IODIDE IN DIOXANE-WATER MIXTURES FROM ELECTROMOTIVE-FORCE MEASUREMENTS

The standard potentials of the silver-silver iodide electrode were measured in 10,20,30 and 40% (w/w) dioxane-water mixtures at 15,25,35 and 45°C. These values have been used to determine the thermodynamic quantities ΔGt°, ΔSt°, ΔHt° for the transfer of H+I- from water to various dioxane-water mixtures. The ionic ΔGt° values for H+, Cl-, Br- and I- are determined using Feakins method. The chemical and electrical contributions of ΔGt° are also calculated using the method proposed by Roy and co-workers. The significance of these thermodynamic functions is discussed in relation to the acid-base character of the solvents. © 1979.