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(m), dioxan(X) 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 ΔG^°_t(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.