Heterogeneous Exchange of Amalgams. II. Hydrogen Ion Concentration Effect on the Zn-Amalgam -Zn++ (S04--) Solution Exchange

Abstract

The effect of hydrogen ion concentration on the exchange of a Zn-amalgam-Zn2+ (S04--) solution in bMh the presence and absence of oxygen has been investigated. The technique of radioactive indicators was used and it was found that in an atmosphere of nitrogen, the exchange rate does not change in the pH 4-6 range. From pH 2-4 the exchange rate is inversely proportional to the hydrogen ion activity. In the presence of oxygen from pH 2-6, zinc from the amalgam dis solves completely. At a partial oxygen pressure of 0.2 atm. at hydrogen ion concentrations ranging from 1 X 10 -s - 2.6 X 10 -2 g. ion 1.- 1 the zinc dissolves by two processes. The principal proceiss due to depolarization takes place by the reaction 02 + 2H20 + 4e- ~ 40H- . At a partial oxygen pressure of 1.0 atm ., zinc dissolves by only one process owing to the depolarization of oxygen by the same reaction