Determination of the silver error in the coulometric titration of acids in various media

Abstract

The dependence of the silver error in coulometric titrations of acids in a one-compartment cell on the solubility of silver halide has been established. The silver error is proportional to the total solubility of silver and inversely dependent on the current density. Because the main contribution to the total titration error is given by the silver error, it is necessary to choose conditions that produce the minimum value. The silver error is below 0.1% when the current density of the cathodic process is at least 10 mA cm^–2. This relationship was tested in solutions of chloride, bromide and iodide in water, methanol, ethanol and acetone. For the aqueous solutions the bromide electrolyte is recommended and, for methanolic solutions, the best results are obtained with chloride ions.