3 As2S3 + 22 HNO3 → 6 H3AsO4 + 9 SO2 + 22 NO + 2 H2O
This is an oxidation-reduction (redox) reaction:
6 AsIII - 12 e- → 6 AsV (oxidation)
9 S-II - 54 e- → 9 SIV (oxidation)
22 NV + 66 e- → 22 NII (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:
- H3AsO4 – Arsenic acid, arsoric acid
- 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