HNO3 (aq) + 4 H2S (g) → NH3 (aq) + 4 S (s) + 3 H2O (l)
This is an oxidation-reduction (redox) reaction:
4 S-II - 8 e- → 4 S0 (oxidation)
NV + 8 e- → N-III (reduction)
H2S is a reducing agent, HNO3 is an oxidizing agent.
Reactants:
- 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.]
- H2S – Hydrogen sulfide
- Other names: D , Ihydrogen monosulfide|Dihydrogen sulfide|Sewer gas|Sulfane|Sulfurated hydrogen|Sulfureted hydrogen|Sulfuretted hydrogen|Sulfur hydride|Hydrosulfuric acid|Hydrothionic acid|Thiohydroxic acid|Sulfhydric acid}} , Hydrosulfuric acid
- Appearance: Colorless gas ; Colourless compressed liquefied gas with characteristic odour of rotten eggs ; Colorless gas with a strong odor of rotten eggs. [Note: Sense of smell becomes rapidly fatigued & can NOT be relied upon to warn of the continuous presence of H2S. Shipped as a liquefied compressed gas.]
Products:
- NH3
- Names: Ammonia , Azane (only intended for use in naming derivatives of ammonia) , Hydrogen nitride
- Appearance: Colourless gas ; Colourless gas or compressed liquefied gas with pungent odour ; Colorless gas with a pungent, suffocating odor. [Note: Shipped as a liquefied compressed gas. Easily liquefied under pressure.]
- S
- H2O – Water, oxidane