Studies in isodielectric solvents. Part 1.—Standard potentials of the silver–silver chloride electrode in the acetonitrile + ethylene glycol solvent system at 25°C

Abstract

Standard potentials (E^θ) of the silver–silver chloride electrode have been determined at 25°C in ethylene glycol and in its approximately isodielectric mixtures with 20, 40 and 60 wt. % acetonitrile, from e.m.f. measurements performed on the cell Pt, H₂(g, 1 atm.)/HCl(m), solvent/Ag–AgCl. Standard free energies of transfer (ΔG^θ_t), of HCl at 25°C from ethylene glycol to acetonitrile + ethylene glycol mixtures, obtained from these measurements have been interpreted in terms of the acid–base nature of the solvents. Comparison of the ΔG^θ_t-composition profile with those of other isodielectric solvent systems has been used to confirm the idea of ion desolvation caused by dipolar aprotic solvents like acetonitrile.