The Anodic Behavior of Silver in Concentrated Chloride Solutions

The processes on the silver electrode during its anodic polarization in concentrated chloride solutions (1,5 - 5,0 M) are identified. The analysis of the potentiodynamic E-I relationships showed, that the anodic polarization depends on the concentration of Cl ions and runs through two steps (peaks A and B). The first step - peak A corresponds to: a/the irreversible electrode reaction involving the adsorption of the reaction product - AgCl in the solution, in which concentration of Cl was less than 2M and b/ the reversible electrode reaction involving the adsorption of the AgCl type species (n=3,4), when the concentration of Cl was more than 4 M. The second step - peak B corresponds to: a/the increase of the passive layer of AgCl showing high porosity and a low ohmic resistance - in the solution in which concentration of Cl was less than 2 M and b/the anodic process, which follows the dissolution-precipitation model, in which the electrochemical reaction of AgCl formation precedes the chemical precipitation of AgCl - in the solution with Cl was more than 4 M. On the basis of experimental functions the values of specific conductivity for the passive layer of AgCl at 4 M and 5 M chloride solutions were calculated. The structure differences of the passive AgCl layer forming in the chloride solutions have been shown by the microscope scanning analysis.