2 KCr2O7 + 28 HBr → 4 CrBr + 11 Br2 + 2 KBr + 14 H2O

This is an oxidation-reduction (redox) reaction:

22 Br-I - 22 e- → 22 Br0 (oxidation)

4 Cr13/2 + 22 e- → 4 CrI (reduction)

HBr is a reducing agent, KCr2O7 is an oxidizing agent.

Reactants:

  • KCr2O7
  • HBr – Hydrogen 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

Products:

  • CrBr
  • 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
  • KBr
    • Names: Potassium bromide source: wikipedia, accessed: 2019-09-27source: wikidata, accessed: 2019-09-02, KBr source: wikidata, accessed: 2019-09-02, Kaliumbromid source: wikidata, accessed: 2019-09-02
    • Appearance: White solid 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