2 SO2 (aq) + 2 CaCO3 (s) + O2 (g) → 2 CaSO4 (s) + 2 CO2 (g)

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:

  • 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
  • CaCO3 – Calcium carbonate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04
    • Other names: Calcite; aragonite; chalk; Lime (material); Limestone; marble; oyster; pearl; source: wikipedia, accessed: 2019-09-27, Calcium salt of carbonic acid source: wikidata, accessed: 2019-09-02, Children's Mylanta Upset Stomach Relief source: wikidata, accessed: 2019-09-02
    • Appearance: Fine white powder; chalky taste source: wikipedia, accessed: 2019-09-27; White powder or pellets source: ICSC, accessed: 2019-09-04
  • 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
  • CO2
    • Names: Carbon dioxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, {{plainlist| source: wikipedia, accessed: 2019-09-27, CO2 source: wikidata, accessed: 2019-09-02
    • Appearance: Colorless gas source: wikipedia, accessed: 2019-09-27; Odourless colourless compressed liquefied gas source: ICSC, accessed: 2019-09-04; Colorless, odorless gas. [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice.] source: NIOSH NPG, accessed: 2019-09-02