Heterocyclic hydroxamic acids. V. Thermodynamics of the interaction of some bivalent metal ions with N-phenyl-2-furohydroxamic acid and its analogues

In recent years, considerable effort has been devoted to physico-chemical studies in non-aqueous and mixed solvents. Most of these have been concerned with solutions in mixed solvents with a view to explaining the effect of a changing solvent composition of the ion—solvent and electrode—solvent interactions. Several workers 1–6] have presented studies of electrode—solvent interactions in water—dioxane, water—glycol, water—alcohols and water—urea mixtures of various compositions, and have reported the role of the permittivity of the medium towards such interactions.In previous studies 3,7–9], we have examined the effect of changing the solvent from pure water to 10, 20, 30 and 40 mass % dioxane + water on the dissociation of acids, dissolution of silver salts and standard potentials of the silver—silver chromate electrode. To extend the work, we now report the results of a determination of the standard potentials of the silver—silver thiocyanate electrode and associated thermodynamic parameters for the electrode reaction in these media. However, various thermodynamic quantities for the electrode reaction of this electrode and the dissolution process of silver thiocyanate are known in water 10] and formamide 11].