The Difference Effect on Magnesium Dissolving in Acids

The difference (Δ) effect on Mg metal was measured in , , and of concentrations between 0.05 and 0.50 N at 25 °C. Generally the effect was positive, but the usual linear relationship between Δ and I existed only at low current densities and high acid concentrations. In and , the positive effect changed to negative at increased current densities and low acid concentration. Attempts to attribute the Δ effect to the anodic expulsion of uncommon valency Mg ions result in unrealistic values of cationic charges for positive values of Δ. The difference effect is explained on the basis of anodic polarization, film disruption, and disintegration of the magnesium anode, i.e. "chunk effect."