2 HClO2 + 3 H2SeO3 → 3 H2SeO4 + Cl2 + H2O

This is an oxidation-reduction (redox) reaction:

3 SeIV - 6 e- → 3 SeVI (oxidation)

2 ClIII + 6 e- → 2 Cl0 (reduction)

H2SeO3 is a reducing agent, HClO2 is an oxidizing agent.

Reactants:

  • HClO2 – Chlorous acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: HClO2 source: wikidata, accessed: 2019-09-02, [ClO(OH)] source: wikidata, accessed: 2019-09-02, HOClO source: wikidata, accessed: 2019-09-02, Chlorite source: wikidata, accessed: 2019-09-02
  • H2SeO3 – Selenous acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Selenic(IV) acid source: wikipedia, accessed: 2019-09-27
    • Other names: Selenious acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, [SeO(OH)2] source: wikidata, accessed: 2019-09-02, Selenige Säure source: wikidata, accessed: 2019-09-02, Monohydrated selenium dioxide source: ICSC, accessed: 2019-09-04
    • Appearance: White hygroscopic crystals source: wikipedia, accessed: 2019-09-27; Colourless hygroscopic crystals source: ICSC, accessed: 2019-09-04

Products:

  • H2SeO4 – Selenic(VI) acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Selenic acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, H2SeO4 source: wikidata, accessed: 2019-09-02, [SeO2(OH)2] source: wikidata, accessed: 2019-09-02
    • Appearance: Colorless deliquescent crystals source: wikipedia, accessed: 2019-09-27
  • Cl2
    • Names: Chlorine source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Molecular chlorine source: NIOSH NPG, accessed: 2019-09-02
    • Appearance: Greenish-yellow compressed liquefied gas with pungent odour source: ICSC, accessed: 2019-09-04; Greenish-yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.] source: NIOSH NPG, accessed: 2019-09-02
  • H2O – Water, 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