2 HgS (s) + 3 O2 (g) → 2 HgO (s) + 2 SO2 (aq)

This is an oxidation-reduction (redox) reaction:

2 S-II - 12 e- → 2 SIV (oxidation)

6 O0 + 12 e- → 6 O-II (reduction)

HgS is a reducing agent, O2 is an oxidizing agent.

Reactants:

  • HgS – Mercury sulfide source: wikipedia, accessed: 2019-09-27
    • Other names: Cinnabar source: wikipedia, accessed: 2019-09-27, Vermilion source: wikipedia, accessed: 2019-09-27, Mercury(II) sulfide source: wikidata, accessed: 2019-09-02
  • O2
    • Names: Dioxygen source: wikidata, accessed: 2019-09-07, Oxygen source: ICSC, accessed: 2019-09-04source: wikidata, accessed: 2019-09-07, Oxygen (liquefied) source: ICSC, accessed: 2019-09-04
    • Appearance: Odourless compressed gas source: ICSC, accessed: 2019-09-04; Liquefied gas. colourless-to-blue extremely cold liquid source: ICSC, accessed: 2019-09-04

Products:

  • HgO – Mercury(II) oxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Mercuric oxide source: wikipedia, accessed: 2019-09-27source: ICSC, accessed: 2019-09-04, Montroydite source: wikipedia, accessed: 2019-09-27, Red mercury source: wikipedia, accessed: 2019-09-27, Mercury (II) oxide source: ICSC, accessed: 2019-09-04
    • Appearance: Yellow or red solid source: wikipedia, accessed: 2019-09-27; Yellow, orange-yellow or red heavy crystalline powder source: ICSC, accessed: 2019-09-04
  • SO2 – Sulfur dioxide source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Sulfurous anhydride source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Sulphur dioxide source: ICSC, accessed: 2019-09-04source: wikidata, accessed: 2019-09-02, Sulfurous acid anhydride source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02
    • Appearance: Colorless gas source: wikipedia, accessed: 2019-09-28; Colourless gas or compressed liquefied gas with pungent odour source: ICSC, accessed: 2019-09-04; Colorless gas with a characteristic, irritating, pungent odor. [Note: A liquid below 14°F. Shipped as a liquefied compressed gas.] source: NIOSH NPG, accessed: 2019-09-02