3 Cu2S (s) + 20 HNO3 (aq) → 6 Cu(NO3)2 (aq) + 3 SO2 (aq) + 8 NO (g) + 10 H2O (l)
This is an oxidation-reduction (redox) reaction:
6 CuI - 6 e- → 6 CuII (oxidation)
3 S-II - 18 e- → 3 SIV (oxidation)
8 NV + 24 e- → 8 NII (reduction)
Cu2S is a reducing agent, Cu2S is a reducing agent, HNO3 is an oxidizing agent.
Reactants:
- Cu2S – Copper(I) Sulphide
- HNO3 – Nitric acid
- Other names: Aqua fortis , Spirit of niter , Eau forte
- Appearance: Colorless, yellow or red fuming liquid ; Colourless-to-yellow liquid with pungent odour ; Colorless, yellow, or red, fuming liquid with an acrid, suffocating odor. [Note: Often used in an aqueous solution. Fuming nitric acid is concentrated nitric acid that contains dissolved nitrogen dioxide.]
Products:
- Cu(NO3)2 – Copper(II) nitrate
- SO2 – Sulfur dioxide
- Other names: Sulfurous anhydride , Sulphur dioxide , Sulfurous acid anhydride
- Appearance: Colorless gas ; Colourless gas or compressed liquefied gas with pungent odour ; Colorless gas with a characteristic, irritating, pungent odor. [Note: A liquid below 14°F. Shipped as a liquefied compressed gas.]
- NO – Nitrogen monoxide , Oxidonitrogen(•) (additive)
- H2O – Water, oxidane