Anodic Reaction of Cuprous Sulfide in Sulfuric Acid Solution

To know the anodic reaction mechnism of cuprous sulfide in sulfuric acid solution, the following experiments were made; the measurements of the electrode potentials, anodic polarization behaviours and galvanostatic polarization behaviours of the Cu2S-CuS sulfide system, and observations of the copper concentration by X-ray microanalyser (XMA) and crystal structure by X-ray reflection of the sulfide electrode surface.(1) The electrode potentials of the Cu2S-CuS sulfide system show three characteristic values for Cu2S, Cu1.8S and CuS sulfide, respectively.(2) Cuprous sulfide was dissolved anodically in sulfuric acid solution through the following two processes; \phantom(1) i(i) Cu2S→CuS+Cu2++2e \phantom(1) (ii) CuS→Cu2++S+2e. (3) The apparent activation energy for the diffusion of copper atom in cuprous sulfide was about 3.4 kcal/mol.