2 CaO + 2 SO2 + O2 → 2 CaSO4

This is an acid-base reaction (neutralization): CaO is a base, SO2 is an acid.

This is an oxidation-reduction (redox) reaction:

2 SIV - 4 e- → 2 SVI (oxidation)

2 O0 + 4 e- → 2 O-II (reduction)

SO2 is a reducing agent, O2 is an oxidizing agent.

Reactants:

  • 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
  • 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
  • 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:

  • 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