Thermodynamics of the amalgam cell: {MexHg1‐x|MeCl(m)| AgCl| Ag} (with Me = K, Rb) in (methanol+water) solvent mixtures

Abstract

AbstractThe electromotive force E of the amalgam cell {MexHg1‐x|MeCl(m)|AgCl|Ag}, where Me = K or Rb, has been measured at the temperature 298.15 K as a function of the molality m of MeCl in (methanol + water) mixed solvents up to 0.8 mass fraction of methanol, with relative permittivities ϵ>40, and as a function of the mole fraction x of Me in amalgam. The respective standard electromotive forces E0m have been determined, together with the mean molal activity coefficients y ± of the relevant MeCl as a function of its molality. For interpolation purposes the E0m values can be expressed as a function of the methanol mass fraction wM by the following polynomials, valid for 0≤wM≤0.8: These results for standard e.m.f.s, interpreted in terms of primary medium effects, lead to primary hydration numbers nhydr = 6.6 for KCl, and = 6.7 for RbCl, in good agreement with previous results using different methods.