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Studies on the liquid junction potential corrections of electrolytes at aqueous + mixed solvent boundaries

Senanayake, G. and Muir, D.M. (1987) Studies on the liquid junction potential corrections of electrolytes at aqueous + mixed solvent boundaries. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 237 (2). pp. 149-162.

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Liquid junction potentials (EJ) generated at the boundaries of various salt bridge/mixed aqueous + organic solutions, have been determined by comparing the measured emf of silver cells with the calculated emf using literature values of transfer activity coefficients γt (Ag+) and γt (Cl−) based on the tetraphenylarsonium-tetraphenylborate (TATB) assumption.

The EJ values have been analyzed in terms of the ion-solvent interaction, determined by ionic transfer Gibbs energies, and the so-called solvent-solvent interaction. The effect of varying the cation, anion, and concentration of bridge electrolyte, is assessed in aqueous acetonitrile (AN), ethanol (EtOH), and dimethylsulfoxide (DMSO). It is concluded that the previously reported solvent-solvent contribution to EJ is merely a correction factor to the ion-solvent interaction contribution due to solvent mixing at the boundary. Four salt bridges (sat. K2SO4 3.5 M KCl, 3.5 M NaClO4, and 0.1 M Et4N-picrate) are compared on the basis of EJ.

The recommended salt bridge for use with mixed aqueous + organic solutions is 3.5 M NaClO4 in water. Appropriate EJ correction factors are presented for emf measurements in mixtures of AN + H2O, EtOH + H2O, and DMSO + H2O.

Item Type: Journal Article
Murdoch Affiliation(s): School of Mathematical and Physical Sciences
Publisher: Elsevier BV
Copyright: © 1987 Published by Elsevier B.V.
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