The Electrode Potential of Zinc Amalgam in Alkaline Zincate Solutions

The electrode potential of zinc amalgams has been measured in potassium hydroxide solutions containing dissolved zincate. Curvature in the Nernst plots was observed at high zincate concentrations in agreement with the results of other workers. The curvature is explained as being due to the dependence of the hydroxyl and zincate ion activity on concentration in strong potassium hydroxide solutions. The data yield a value of −1.205V ( vs. SHE) for the standard potential of the zinc, zincate ion electrode (I.U.P.A.C.—Stockholm convention) and −205.86 kcal for the free energy of formation of the zincate ion at 25°C.