Standard potentials of the silver–silver bromide electrode in propan-2-ol + water mixtures. Free energies and entropies of transfer of hydrobromic acid

Abstract

Standard potentials (E^⊖) of the Ag–AgBr electrode in aqueous mixtures of 10, 20, 30 and 50 wt % propan-2-ol have been determined from e.m.f. measurements on the cell Pt, H₂(g, 1 atm)| HBr(m), solvent | AgBr–Ag at seven temperatures from 5 to 35°C at 5°C intervals. These values were used to evaluate standard free energies (ΔG^⊖_t) and entropies (ΔS^⊖_t) of transfer of HBr from water to these solvents. The observed broad hump and pronounced maximum in the (ΔG^⊖_t)- and T(ΔS^⊖_t)-composition profiles respectively, being similar to those in t-butanol + water mixtures, are indicative of the similar effects of ion-solvent interactions as well as of the structural features of these solvents.