As2O + 4 Br2 + 7 H2O 2 H3AsO4 + 8 HBr

This is an oxidation-reduction (redox) reaction:

8 Br0 + 8 e- 8 Br-I (reduction)

2 AsI - 8 e- 2 AsV (oxidation)

Br2 is an oxidizing agent, As2O is a reducing agent.

Reactants:

  • As2O
  • Br2
    • Names: Bromine source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Molecular bromine source: NIOSH NPG, accessed: 2019-09-02
    • Appearance: Fuming red-to-brown liquid with pungent odour source: ICSC, accessed: 2019-09-04; Dark reddish-brown, fuming liquid with suffocating, irritating fumes. source: NIOSH NPG, accessed: 2019-09-02
  • 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

Products:

  • H3AsO4Arsenic acid, arsoric acid source: wikipedia, accessed: 2019-09-27
    • Other names: Arsenic acid source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Orthoarsenic acid source: wikipedia, accessed: 2019-09-27, Desiccant L-10 source: wikipedia, accessed: 2019-09-27
    • Appearance: White translucent crystals | hygroscopic. source: wikipedia, accessed: 2019-09-27; Colourless-to-pale-green-viscous liquid source: ICSC, accessed: 2019-09-04
  • HBrHydrogen bromide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Bromane source: wikipedia, accessed: 2019-09-27source: wikipedia, accessed: 2019-09-27
    • Other names: Hydrobromic acid source: wikipedia, accessed: 2019-09-27source: ICSC, accessed: 2019-09-04, Hydronium bromide source: wikipedia, accessed: 2019-09-27, HBr source: wikidata, accessed: 2019-09-02
    • Appearance: Colorless gas source: wikipedia, accessed: 2019-09-27; Colorless/faint yellow liquid source: wikipedia, accessed: 2019-09-27; Colourless compressed liquefied gas with pungent odour source: ICSC, accessed: 2019-09-04; Colorless gas with a sharp, irritating odor. [Note: Shipped as a liquefied compressed gas. Often used in an aqueous solution.] source: NIOSH NPG, accessed: 2019-09-02