Cu2S (s) + 8 HNO3 (aq) → 2 Cu(NO3)2 (aq) + 4 NO2 (l) + S (s) + 4 H2O (l)
This is an oxidation-reduction (redox) reaction:
2 CuI - 2 e- → 2 CuII (oxidation)
S-II - 2 e- → S0 (oxidation)
4 NV + 4 e- → 4 NIV (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
- NO2 – Nitrogen dioxide
- Other names: Nitrogen(IV) oxide , Deutoxide of nitrogen , Nitrogen peroxide
- Appearance: Brown gas ; Reddish-brown gas or brown or yellow liquid with pungent odour ; Yellowish-brown liquid or reddish-brown gas (above 70°F) with a pungent, acrid odor. [Note: In solid form (below 15°F) it is found structurally as N2O4.]
- S
- H2O – Water, oxidane