2 ClO₃^- + SO₂ → 2 ClO₂ + SO₄^2-

This is an oxidation-reduction (redox) reaction:

SO₂ is a reducing agent, ClO₃^- is an oxidizing agent.

Reactants:

• ClO₃^-
• SO₂ – Sulfur dioxide
  • Other names: Sulfurous anhydride , Sulphur dioxide , Sulfurous acid anhydride ... show moreSulfurous oxide , Sulfur oxide , Sulphur dioxide , sulfur dioxide , SO2 , R-764 show less
  • Appearance: Colorless gas ; Colourless gas or compressed liquefied gas with pungent odour ; Colorless gas with a characteristic, irritating, pungent odor. [Note: A liquid below 14°F. Shipped as a liquefied compressed gas.]

Products:

• ClO₂ – Chlorine dioxide , 4-chlorane (substitutive) OR Dioxidochlorine(•) (additive) -->
  • Other names: Chlorine(IV) oxide , Chlorine oxide , Chlorine peroxide ... show moreO2Cl(.) , [ClO2](.) , (OClO)(.) , Chlorine(IV)oxide show less
  • Appearance: Yellow to reddish gas ; Red-yellow gas with pungent odour ; Yellow to red gas or a red-brown liquid (below 52°F) with an unpleasant odor similar to chlorine and nitric acid.
• SO₄^2- – Sulfate
  • Other names: Sulfate ion , Sulphate ion , Sulphate