Thermodynamics of Hydrobromic Acid in Dioxan+Water Mixtures from Electromotive Force Measurements at Different Temperatures

Abstract

Electromotive force measurements of the cell Pt, H2/HBr(z>i), dioxan(A3 H2O(y)/AgBr/Ag have been made at 15, 25, 35 and 45“C for solvent compositions X = 10, 20, 30, 40, 60 %(w/w) of dioxan. These have been used to evaluate the standard potentials of the cell, the mean activity coefficient of HBr (molal scale) and the thermodynamic functions (mole-fraction scale) for the transfer of HBr from water to the respective dioxan+water media. The AG’ (free energy of transfer of the acid from water to various solvents) values along with those for hydrochloric acid, are briefly discussed in relation to ion solvation.