THE AMPEROMETRIC-TITRATION OF COPPER(II) SULFATE WITH POTASSIUM-PERMANGANATE IN SURFACTANT SUSPENSIONS

It has been demonstrated that it is possible, in the presence of a cat ionic surfactant, to oxidize copper(II) sulfate (CuSO4.5H(2)O) with po tassium permanganate in aqueous sodium hydroxide solutions and to oxid ize the solid copper(II) sulfate with solid potassium permanganate in methylene chloride. Presumably the surfactant solubilizes the solids a nd protects the unusual valence from reaction with water. In both solv ents, the rate of reaction was fast enough to be followed with an ampe rometric titration. The stoichiometric reactions in these solvents wer e found to involve one potassium permanganate for three copper(II) sul fates, indicating that copper(II) was oxidized to copper(III) while pe rmanganate was reduced to manganese(IV). The results show that both io ns and solids, suspended and coated with Surfactants, can react rapidl y enough for the reactions to be used in titrations and that copper(II I) can be formed by chemical reaction and stabilized by a cationic sur factant film.