Stepwise determination of metallic copper, cuprous oxide and cupric oxide

Abstract

A method for the determination of metallic copper, cuprous oxide and cupric oxide was estblished. In order to separate copper from copper oxides, ca. 0.1 g of sample was dissolved with 50 ml of (0.002~0.1)N ceric sulfate, depending on the cuprous oxide contents, in a nitrogen atmosphere. After the dissolution by shaking for ca. 1 min, the residue (metallic copper) was filtered off by suction and put it back into the original flask together with the filter paper. It was dissolved by digesting with 9.4% ferric chloride solution in 1.5 M hydrochloric acid in the nitrogen atmosphere for 3 h at (50~60) °C. The Fe2+ formed was titrated with ceric sulfate. Determination of cuprous oxide was carried out as follows. A sample was dissolved in the ferric chloride solution in the nitrogen atmosphere. The Fe2+ formed was titrated as discribed above, the result giving a sum of metallic copper and cuprous oxide. Cuprous oxide content was then calculated by the subtraction of metallic copper content from the sum of metallic copper and cuprous oxide. The determination of total copper was performed spectrophotometrically at 810 nm as copperaquo ion complex in nitric acid media. The determination of cupric copper was accomplished by the subtraction of metallic copper and cuprous copper from the total copper. The procedure established was applied to the determination of metallic, cuprous and cupric copper in copper powder and copper oxide catalyzer. The coefficient of variation for the analysis of the copper oxide catalyzer came out as 10.7% for metallic copper, 2.6% for cuprous oxide, 3.7% for cupric oxide and 0.27% for total copper. © 1979, The Japan Society for Analytical Chemistry. All rights reserved.