Cr2O72+ + 5 SO2 + 4 H3O+ 2 (Cr)3+ + 5 SO3 + 6 H2O

This is an oxidation-reduction (redox) reaction:

5 SIV - 10 e- 5 SVI (oxidation)

2 CrVIII + 10 e- 2 CrIII (reduction)

SO2 is a reducing agent, Cr2O72+ is an oxidizing agent.

Reactants:

  • Cr2O72+
  • SO2Sulfur 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
  • H3O+
    • Names: Hydronium source: wikidata, accessed: 2019-09-07, Hydroxonium source: wikidata, accessed: 2019-09-07, H3O(+) source: wikidata, accessed: 2019-09-07

Products:

  • Cr3+
  • SO3Sulfur trioxide source: wikipedia, accessed: 2019-09-28source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Sulfonylideneoxidane source: wikipedia, accessed: 2019-09-28
    • Other names: Sulfuric anhydride source: wikipedia, accessed: 2019-09-28, Sulfur(VI) oxide source: wikipedia, accessed: 2019-09-28, SO3 source: wikidata, accessed: 2019-09-02
    • Appearance: Colorless to white crystalline solid which will fume in air.{{ source: wikipedia, accessed: 2019-09-28; Fuming hygroscopic colourless liquid or colourless-to-white crystals source: ICSC, accessed: 2019-09-04
  • H2OWater, oxidane source: wikipedia, accessed: 2019-09-27
    • Other names: Water (H2O) source: wikipedia, accessed: 2019-09-27, Hydrogen hydroxide (HH or HOH) source: wikipedia, accessed: 2019-09-27, Hydrogen oxide source: wikipedia, accessed: 2019-09-27
    • Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas source: wikipedia, accessed: 2019-09-27