Ag2S + 4 HNO3 → 2 AgNO3 + 2 NO2 + S + 2 H2O
This is an oxidation-reduction (redox) reaction:
S-II - 2 e- → S0 (oxidation)
2 NV + 2 e- → 2 NIV (reduction)
Ag2S is a reducing agent, HNO3 is an oxidizing agent.
Reactants:
- Ag2S – Silver(I) sulfide, Silver sulfide
- 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.]
- Other names: Aqua fortis
Products:
- AgNO3 – Silver(I) nitrate, Silver 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.]
- Other names: Nitrogen(IV) oxide
- S
- H2O – Water, oxidane