The Possibility of obtaining E.M.F. directly from Acid-Base Reactions: Electrodes of the Third Kind reversible to Alkaline Earth and Other Ions

Abstract

SOME years ago Shedlovsky^1,2 suggested that proton transfer reactions could give rise directly to e.m.f., and apparently confirmed this idea by demonstrating that a glass electrode, coated with lauric acid and barium laurate, acted as a barium electrode. There is a simpler explanation of this result, however: namely, the glass electrode with lauric acid and barium laurate acts as an electrode of the third kind. In a barium chloride solution saturated with these substances, the activities of barium and hydrogen ions must be related by the equation: k representing the thermodynamic solubility product. In such solutions the glass electrode, responding to hydrogen ion activity in the normal way, would therefore appear to act as a barium electrode.