Thermodynamics of Hydrochloric Acid in Dioxan + Water Mixtures from Electromotive Force Measurements

Abstract

Electromotive force measurements using the cell Pt|H2(g,1 atm)|HCl(m), dioxan(X), H2O(Y)|AgCl(s)|Ag have been made at nine different temperatures from 15 to 55°C at five intervals in eighteen dioxan + water solvent mixtures. These have been used to evaluate the standard potentials of the Ag,AgCl electrode, the standard thermodynamic functions for the cell reaction, the primary medium effects of various solvents upon HCl and the standard thermodynamic quantities for the transfer of one mole of HCl from water to the respective dioxan + water media. The standard molal potential in each solvent has been represented as a function of temperature. The results have been discussed in relation to the acid–base properties and the breakdown of the structure of water on the addition of dioxan.