Salt effects in reduction of inorganic anions at dropping mercury electrode

Abstract

The increase in the electroreduction current of the S₂O^2–₈, Fe(CN)^3–₆, S₄O^2–₆ and H₂P₂O^2–₈ ions produced by the perchlorates of alkali-metal cations has been measured. This increase cannot be due either to the formation of ion pairs in the bulk of the solution or to the elimination of a negative migration current. There is a parallelism between the efficiency of the cations on the electroreduction and on the rate of homogeneous reactions involving the same anions. It is suggested that the mechanism of these salt effects is essentially the same at the mercury-solution interface as in the anion-anion activated complex. The causes of the different relative efficiencies of the different cations are discussed.