Standard Potentials of Silver-Silver Iodide Electrode in Water + Propylene Glycol Mixtures by Electromotive Force Measurements and Related Thermodynamic Quantities

The standard potentials of the silver-silver Iodide electrode have been determined in the temperature range 15–45 °C in 20, 40, 75, and 90 wt % propylene glycol from emf measurements of the cells Pt|H2(g, 1 atm)|HBO2 (m1, NaBO2 (m2), KBr (m3) (In water + propylene glycol mixtures)|AgBr|Ag and Pt|H2(g, 1 atm)|HBO2(m1, NaBO2 (m2), CsI (m3) (In water + propylene glycol mixtures)|AgI|Ag. The standard molal potentials, sEm°, in the various solvent mixtures have been expressed as a function of temperature. The various thermodynamic parameters accompanying the transfer of HI from water to these solvents at 25 °C are reported. The variation of these parameters with solvent composition has been discussed In terms of the basicity of the solvent and the structural effects of the solvent mixtures on the transfer process. The transfer free energies of the proton and the iodide Ion have been evaluated at 25 °C, on the basis of the ferrocene reference method in these media. © 1985, American Chemical Society. All rights reserved.