HgS + 2 HNO3 + 4 HCl → H2HgCl4 + SO2 + 2 NO + 2 H2O
This is an oxidation-reduction (redox) reaction:
S-II - 6 e- → SIV (oxidation)
2 NV + 6 e- → 2 NII (reduction)
HgS is a reducing agent, HNO3 is an oxidizing agent.
Reactants:
- HgS – Mercury 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.]
- HCl – Chlorane , Hydrogen chloride
- Other names: Hydrochloric acid , M , Uriatic acid
- Appearance: Colorless, transparent liquid, fumes in air if concentrated ; Colorless gas ; Colourless compressed liquefied gas with pungent odour ; Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.]
Products:
- H2HgCl4
- 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