Se + 2 Cl2 + 3 H2O H2SeO3 + 4 HCl

This is an oxidation-reduction (redox) reaction:

Se0 - 4 e- SeIV (oxidation)

4 Cl0 + 4 e- 4 Cl-I (reduction)

Se is a reducing agent, Cl2 is an oxidizing agent.

Reactants:

  • Se
    • Names: Selenium source: wikidata, accessed on: 2019-09-07source: ICSC, accessed on: 2019-09-04source: NIOSH NPG, accessed on: 2019-09-02, Se source: wikidata, accessed on: 2019-09-07, Selen source: wikidata, accessed on: 2019-09-07
    • Appearance: Grey solid in various forms source: ICSC, accessed on: 2019-09-04; Amorphous or crystalline, red to gray solid. [Note: Occurs as an impurity in most sulfide ores.] source: NIOSH NPG, accessed on: 2019-09-02
  • Cl2
    • Names: Chlorine source: ICSC, accessed on: 2019-09-04source: NIOSH NPG, accessed on: 2019-09-02, Molecular chlorine source: NIOSH NPG, accessed on: 2019-09-02
    • Appearance: Greenish-yellow compressed liquefied gas with pungent odour source: ICSC, accessed on: 2019-09-04; Greenish-yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.] source: NIOSH NPG, accessed on: 2019-09-02
  • H2OWater, oxidane source: wikipedia, accessed on: 2019-09-27
    • Other names: Water (H2O) source: wikipedia, accessed on: 2019-09-27, Hydrogen hydroxide (HH or HOH) source: wikipedia, accessed on: 2019-09-27, Hydrogen oxide source: wikipedia, accessed on: 2019-09-27
    • Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas source: wikipedia, accessed on: 2019-09-27

Products:

  • H2SeO3Selenous acid source: wikipedia, accessed on: 2019-09-27source: wikidata, accessed on: 2019-09-02source: ICSC, accessed on: 2019-09-04, Selenic(IV) acid source: wikipedia, accessed on: 2019-09-27
    • Other names: Selenious acid source: wikipedia, accessed on: 2019-09-27source: wikidata, accessed on: 2019-09-02source: ICSC, accessed on: 2019-09-04, [SeO(OH)2] source: wikidata, accessed on: 2019-09-02, Selenige Säure source: wikidata, accessed on: 2019-09-02, Monohydrated selenium dioxide source: ICSC, accessed on: 2019-09-04
    • Appearance: White hygroscopic crystals source: wikipedia, accessed on: 2019-09-27; Colourless hygroscopic crystals source: ICSC, accessed on: 2019-09-04
  • HClChlorane source: wikipedia, accessed on: 2019-09-27, Hydrogen chloride source: wikipedia, accessed on: 2019-09-27source: wikidata, accessed on: 2019-09-02source: ICSC, accessed on: 2019-09-04source: NIOSH NPG, accessed on: 2019-09-02
    • Other names: Hydrochloric acid source: wikipedia, accessed on: 2019-09-27source: NIOSH NPG, accessed on: 2019-09-02, Hydrochloric acid gas source: wikipedia, accessed on: 2019-09-27, HCl source: wikidata, accessed on: 2019-09-02
    • Appearance: Colorless, transparent liquid, fumes in air if concentrated source: wikipedia, accessed on: 2019-09-27; Colorless gas source: wikipedia, accessed on: 2019-09-27; Colourless compressed liquefied gas with pungent odour source: ICSC, accessed on: 2019-09-04; Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.] source: NIOSH NPG, accessed on: 2019-09-02