Thermodynamics of the amalgam cell {KxHg1-x|KCl(m)|AgCl|Ag} and primary medium effects upon KCl in {ethylene glycol + water}, {acetonitrile + water}, and {1,4-dioxane + water} solvent mixtures

The emf. E of the amalgam cell {KxHg1-x|KCl(m)|AgCl|Ag} has been measured as a function of the mole fraction x of K metal in amalgams and of the molality m of KCl in (ethylene glycol + water), (acetonitrile + water), and (1,4-dioxane + water) solvent mixts. contg. up to 0.8 mass fraction of the org. component, at the temp. 298.15 K. The resp. std. electromotive forces Em0 have been detd., together with the relevant activity coeffs. γ± as a function of KCl molality. A new scheme is here implemented for verification of the internal consistency of the γ± results in terms of complementary pairs of concn. cells with transference. For interpolation purposes, the Em0 dependence on the mass fraction w of the org. component of the solvent mixt. within the range explored may be expressed by: Em0/V = 2.1977 - 0.0872wG - 0.0313wG2, Em0/V = 2.1978 - 0.1181wA + 0.0257wA2 - 0.217wA3, Em0/V = 2.1977 = 0.209wD + 0.274wD2 - 0.733wD3, (the subscripts denoting G = ethylene glycol, A = acetonitrile, and D = 1,4-dioxane, resp.) which reproduce the obsd. Em0 values to within ±0.3 mV. Anal. of the relevant primary medium effects upon KCl leads to a primary hydration no. of 6.6 for KCl, in good agreement with previous results based on different methods.