H3AsO4 + 2 KI → K2HAsO3 + I2 + H2O

This is an oxidation-reduction (redox) reaction:

AsV + 2 e- → AsIII (reduction)

2 I-I - 2 e- → 2 I0 (oxidation)

H3AsO4 is an oxidizing agent, KI is a reducing agent.

Reactants:

  • H3AsO4 – Arsenic 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
  • KI
    • Names: Potassium iodide source: wikidata, accessed: 2019-09-02, KI source: wikidata, accessed: 2019-09-02, Thyrosafe source: wikidata, accessed: 2019-09-02

Products:

  • K2HAsO3
  • I2
    • Names: Iodine source: ICSC, accessed: 2019-09-04source: NIOSH NPG, accessed: 2019-09-02, Jod source: ICSC, accessed: 2019-09-04, Iode source: ICSC, accessed: 2019-09-04
    • Appearance: Bluish black or dark purple crystals with pungent odour source: ICSC, accessed: 2019-09-04; Violet solid with a sharp, characteristic odor. 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