Analysis of copper alloys by controlled potential electrolysis

Studies on controlled potential electroanalysis. IX

Abstract

The principal components of copper-zinc alloy have been investigated by means of a successive electrolytic analysis by the limited cathode potential method. Copper alloys containing few impurities were dissolved in nitric acid, and the solution was evaporated to dryness after the addition of sulfuric acid. It was found that the electrolytic determination was possible by using this limited cathode potential method with a platinum electrode and one of the following supporting electrolytes:
(1) The cathode potential is limited to -0.20 V vs. S. C. E. with the use of 0.4N sulfuric acid for electrolytic determination of copper. The residual electrolyte is neutralized with ammonia; then ammonia is added in excess to 1.2N, in which electrolytic determination of zinc is made by using a copper-plated platinum electrode at a limited cathode potential of -1.40 Vvs. S. C. E..
(2) The copper is determined in a solution containing 0.4M sodium tartrate and 0.1M sodium acid tartrate at a limited cathode potential of-0.50V vs. S. C. E., then electrolytic determination of zinc is carried out at a limited cathode potential of -1.20 V vs. S. C. E...
(3) The copper is determined in a solution containing 1.2N ammonia and 0.46M ammonium chloride at a limited cathode potential of -0.60 V vs. S. C. E.; then the zinc is determined under a limited cathode potential of -1.50 V vs. S. C. E...
In the case of nickel-copper alloy, the sample is dissolved in nitric acid, evaporated to dryness after addition of sulfuric acid; and the residue is dissolved in water, and the copper is determined in an electrolyte containing 1.2N ammonia and 0.2M ammonium sulfate under a limited cathode potential of -0.60 V vs. S. C. E.. Then the nickel is determined under a limited cathode potential of -1.15 V vs. S. C. E. at 60°C. Good results were obtained.