For the amalgam cell {MxHg1 - x|MCl2 (m)|AgCl |Ag} (with M = Sr, Ba) the potential difference E has been measured as a function of the mole fraction xM of the metal M in amalgams and of the molality m of MCl2 in {methanol + water} and {ethanol + water} solvent mixtures Z = {A + W} with mass fractions of alcohol wA ≤ 0.50 of alcohol, at temperature 298.15 K. The respective molal-scale standard potential differences Em° have been determined together with the relevant activity coefficients γ± as functions of the MCl2 molality. The Em° dependence on the alcohol mole fraction in the solvent mixture within the ranges explored turns out to be linear for both of these two metals M in the amalgams studied. Of course, also the molal-scale standard Gibbs free energy change (ΔG W→Z°)m=2F(WEm°- ZEm°), which constitutes the "primary medium effect" upon transferring MCl2 from pure water to the (alcohol + water) mixture, is linear in xA. In the same context, following Feakins and French's treatment, which implies volume fraction statistics, the relevant primary medium effects upon MCl2 on the mol • dm -3 scale have been analysed in terms of the expected linear relation of (ΔGW→Z°)c=2F(WE c°-ZEc°) against the logarithm of water volume fraction, leading to primary hydration numbers for SrCl2 and BaCl2, respectively, in acceptable agreement with Bockris' data based on different methods.

Thermodynamics of amalgam cells [M-Amalgam|MCl2 (m)|AgCl|Ag] (M = Sr, Ba) and primary medium effects in (methanol+water) and (ethanol+water) solvent mixtures / L. Falciola, P.R. Mussini, T. Mussini, A. Vimercati. - In: JOURNAL OF CHEMICAL THERMODYNAMICS. - ISSN 0021-9614. - 37:4(2005), pp. 363-369.

Thermodynamics of amalgam cells [M-Amalgam|MCl2 (m)|AgCl|Ag] (M = Sr, Ba) and primary medium effects in (methanol+water) and (ethanol+water) solvent mixtures

L. Falciola
Primo
;
P.R. Mussini
Secondo
;
T. Mussini
Penultimo
;
2005

Abstract

For the amalgam cell {MxHg1 - x|MCl2 (m)|AgCl |Ag} (with M = Sr, Ba) the potential difference E has been measured as a function of the mole fraction xM of the metal M in amalgams and of the molality m of MCl2 in {methanol + water} and {ethanol + water} solvent mixtures Z = {A + W} with mass fractions of alcohol wA ≤ 0.50 of alcohol, at temperature 298.15 K. The respective molal-scale standard potential differences Em° have been determined together with the relevant activity coefficients γ± as functions of the MCl2 molality. The Em° dependence on the alcohol mole fraction in the solvent mixture within the ranges explored turns out to be linear for both of these two metals M in the amalgams studied. Of course, also the molal-scale standard Gibbs free energy change (ΔG W→Z°)m=2F(WEm°- ZEm°), which constitutes the "primary medium effect" upon transferring MCl2 from pure water to the (alcohol + water) mixture, is linear in xA. In the same context, following Feakins and French's treatment, which implies volume fraction statistics, the relevant primary medium effects upon MCl2 on the mol • dm -3 scale have been analysed in terms of the expected linear relation of (ΔGW→Z°)c=2F(WE c°-ZEc°) against the logarithm of water volume fraction, leading to primary hydration numbers for SrCl2 and BaCl2, respectively, in acceptable agreement with Bockris' data based on different methods.
Settore CHIM/02 - Chimica Fisica
Settore CHIM/01 - Chimica Analitica
2005
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/14872
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