As2S3 + 28 HNO3 → 2 HAsO3 + 3 H2SO4 + 28 NO2 + 10 H2O
This is an oxidation-reduction (redox) reaction:
2 AsIII - 4 e- → 2 AsV (oxidation)
3 S-II - 24 e- → 3 SVI (oxidation)
28 NV + 28 e- → 28 NIV (reduction)
As2S3 is a reducing agent, As2S3 is a reducing agent, HNO3 is an oxidizing agent.
Reactants:
- As2S3 – Arsenic trisulfide
- 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:
- HAsO3
- H2SO4 – Sulfuric acid
- 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.]
- H2O – Water, oxidane