A Further Demonstration of Sulfite-Induced Redox Cycling of Metal Ions Initiated by Shaking

Abstract

Details of a fascinating laboratory demonstration of the sulfite-induced redox cycling of Ni(II)/Ni(III), which is initiated by shaking the solution in the presence of air, are reported. The balance between the sulfite and oxygen concentration controls the direction of the overall reaction. The dissolved oxygen is used during the rapid sulfite-induced oxidation of the metal ion or complex, as well as during the subsequent reduction by sulfite and the oxidation of sulfite to sulfate. Shaking the solution in the presence of air restores the dissolved oxygen concentration, and the oxidation-reduction cycle occurs again.