Thermodynamic studies of hydrochloric acid in 1,2-dimethoxyethane and its aqueous mixtures from electromotive force measurements

Abstract

The standard potentials of the Ag,AgCl electrode in 1,2-dimethoxyethane (DME) and in nineteen DME + water solvent mixtures have been determined at nine temperatures from 15 to 55 °C, using cells of the type Pt | H₂(g, 1 atm)| HCl(m), solvent | AgCl | Ag by an extrapolation method making use of the extended terms of the Debye–Hückel theory. In solvents of high DME content, where the dielectric constant is small, it was necessary to correct for ion-pair formation. The standard potential in each solvent has been represented as a function of temperature. The standard thermodynamic functions for the cell reaction and the primary medium effects of various solvents upon HCl have been evaluated. The standard thermodynamic quantities for the process of transfer of HCl from water to each of the other media have been calculated from the values of the standard potential on the mole-fraction scale and their temperature coefficients for the respective solvents. The results have been interpreted in terms of ion–solvent interactions.