Standard potentials of M/M+(M = Li, Na, K, Rb or CS) electrodes in dimethyl sulphoxide + water mixtures at 25°C and related ion-solvent interactions in the solvents
- 1 January 1974
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 70, 1452-1460
- https://doi.org/10.1039/f19747001452
Abstract
The standard electrode potentials (sE°) of M/M+(M = Li, Na, K, Rb and Cs) electrodes in aqueous solutions of dimethyl sulphoxide (DMSO)(containing 10, 20, 40 and 60 wt. % DMSO) have been determined at 25°C from e.m.f. measurements of cells of the type: M(Hg)|MCl(m), solvent| AgCl—Ag, obtaining the activity of metals in amalgams with the help of a similar type of cell in water. The free energies of transfer of MCl, δG° t(MCl)(mole fraction scale) from water to each of these solvents computed from these values and those of sE° Ag—AgCl obtainable from the literature, rise sharply from Li+ to Na+, and fall from Rb+ to Cs+ with a maximum between Na+ and Rb+. This is considered as due to the superimposition of “soft—soft” interactions on the “electrostatic interactions” between the ions and the negative charge centres of hydrogen-bonded solvent complexes. The ΔG° t(i) values for individual ions, obtained by a method of “simultaneous extrapolation” are shown to be largely determined by the “acid-base” type ion-solvent interactions as observed in methanol + water mixtures.Keywords
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