4 HgS + 4 CaO → 4 Hg + 3 CaS + CaSO4

This is an oxidation-reduction (redox) reaction:

S-II - 8 e- → SVI (oxidation)

4 HgII + 8 e- → 4 Hg0 (reduction)

HgS is a reducing agent, HgS 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
  • CaO – Calcium oxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02
    • Other names: Quicklime source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Burnt lime source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Unslaked lime source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02
    • Appearance: White to pale yellow/brown powder source: wikipedia, accessed: 2019-09-27; White hygroscopic crystalline powder source: ICSC, accessed: 2019-09-04; White or gray, odorless lumps or granular powder. source: NIOSH NPG, accessed: 2019-09-02

Products:

  • Hg
    • Names: Mercury source: wikidata, accessed: 2019-09-07source: ICSC, accessed: 2019-09-04, Hg source: wikidata, accessed: 2019-09-07, Quicksilver source: wikidata, accessed: 2019-09-07source: ICSC, accessed: 2019-09-04
    • Appearance: Odourless heavy mobile silvery liquid metal source: ICSC, accessed: 2019-09-04
  • CaS – Calcium sulfide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Calcium monosulfide source: wikipedia, accessed: 2019-09-27, Hepar calcies source: wikipedia, accessed: 2019-09-27, Sulfurated lime source: wikipedia, accessed: 2019-09-27, Oldhamite source: wikipedia, accessed: 2019-09-27
    • Appearance: White crystals | hygroscopic source: wikipedia, accessed: 2019-09-27
  • CaSO4
    • Names: Calcium sulfate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: NIOSH NPG, accessed: 2019-09-02, Plaster of Paris source: wikipedia, accessed: 2019-09-27, Drierite source: wikipedia, accessed: 2019-09-27
    • Appearance: White solid source: wikipedia, accessed: 2019-09-27; White hygroscopic powder or crystalline powder source: ICSC, accessed: 2019-09-04; Odorless, white powder or colorless, crystalline solid. [Note: May have blue, gray, or reddish tinge.] source: NIOSH NPG, accessed: 2019-09-02