Hmmm...solution of copper sulfide? copper sulfide has apretty low solubility product (Ksp(CuS) = 1.3×10-3 6
Sulfide is partially oxidized to sulfate with dil. nitric acid.
S is oxidized to S8
S + 4 O2
+ 8 H2
Why is this so when both have an oxidation number of 2 to begin with?
I don't know if I understood the question, but I think that it depends on the strength of the oxidation agent.