Cr2(SO4)3 + 5 KI + KIO3 + 3 H2O → 2 Cr(OH)3 + 3 K2SO4 + 3 I2

This is an oxidation-reduction (redox) reaction:

5 I-I - 5 e- → 5 I0 (oxidation)

IV + 5 e- → I0 (reduction)

KI is a reducing agent, KIO3 is an oxidizing agent (synproportionation (comproportionation)).

Reactants:

  • Cr2(SO4)3 – Chromium(III) sulfate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Basic chromium sulfate source: wikipedia, accessed: 2019-09-27, Chromic sulfate source: wikipedia, accessed: 2019-09-27
    • Appearance: Reddish-brown crystals (anhydrous), purple crystals (hydrated) source: wikipedia, accessed: 2019-09-27
  • KI
    • Names: Potassium iodide source: wikidata, accessed: 2019-09-02, KI source: wikidata, accessed: 2019-09-02, Thyrosafe source: wikidata, accessed: 2019-09-02
  • KIO3 – Potassium iodate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Iodic acid source: wikipedia, accessed: 2019-09-27, Potassium salt source: wikipedia, accessed: 2019-09-27, KIO3 source: wikidata, accessed: 2019-09-02
    • Appearance: White crystalline powder source: wikipedia, accessed: 2019-09-27
  • 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

Products:

  • Cr(OH)3 – Chromium(3+) hydroxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02
    • Other names: Chromium(III) hydroxide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Chromium (iii) hydroxide hydrate source: ICSC, accessed: 2019-09-04, Cr(OH)3 source: wikidata, accessed: 2019-09-02, Chromic (III) hydroxide hydrate source: ICSC, accessed: 2019-09-04
    • Appearance: Green, gelatinous precipitate source: wikipedia, accessed: 2019-09-27; Blue-to-green powder or black particles source: ICSC, accessed: 2019-09-04
  • K2SO4
    • Names: Potassium sulfate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04, Potassium sulphate source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, Dipotassium sulfate source: wikidata, accessed: 2019-09-02source: ICSC, accessed: 2019-09-04
    • Appearance: White solid source: wikipedia, accessed: 2019-09-27; Colourless-to-white crystals source: ICSC, accessed: 2019-09-04
  • 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