Abstract
The standard potentials of the Ag—AgI electrode in twenty ethylene glycol—water mixtures covering the whole range of solvent composition have been determined from the e.m.f. measurements of the cell Pt¦H2(g, 1 atm)¦HOAc (m 1), NaOAc (m 2), KI(m 3), solvent¦AgI¦Ag at nine different temperatures ranging from 15 to 55°C. The temperature variation of the standard e.m.f. has been utilized to compute the standard thermodynamic functions for the cell reaction, the primary medium effects of various solvents upon HI, and the standard thermodynamic quantities for the transfer of HI from the standard state in water to the standard states in the respective solvent media. The chemical effects of solvents on the transfer process have been obtained by subtracting the electrostatic contributions from the total transfer quantities. The results have been discussed in the light of ion—solvent interactions as well as the structural changes of the solvents.
Zusammenfassung
Es wurden die Standardpotentiale der Ag—AgI Elektrode in 20 Ethylenglycol—Wasser-Mischungen bei 9 Temperaturen (15–55°C) mit der Zelle Pt¦H2 (g, 1 atm)¦HOAc (m 1), NaOAc (m 2), KI (m 3), solvent¦AgI¦Ag gemessen. Aus der Temperaturabhängigkeit wurden die thermodynamischen Funktionen für die Zellenreaktion, die primären Lösungsmitteleffekte auf HI und die thermodynamischen Größen für den Transfer von HI aus dem Standardzustand in Wasser in den Standardzustand im entsprechenden Lösungsmittelgemisch errechnet; die chemischen Effekte erhielt man durch Abzug der elektrostatischen Beiträge zu den Gesamttransfergrößen. Die Ergebnisse werden sowohl im Licht von Ionen—Lösungsmittel-Wechselwirkungen als auch von Änderungen in der Lösungsmittelstruktur diskutiert.
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Elsemongy, M.M., Abdel-Khalek, A.A. Thermodynamic studies of hydriodic acid in ethylene glycol-water mixtures from electromotive force measurements. Monatsh Chem 114, 891–905 (1983). https://doi.org/10.1007/BF00799950
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DOI: https://doi.org/10.1007/BF00799950