2 Cr2O7- + 28 H3O+ + 14 (Br)- 4 (Cr)3+ + 42 H2O + 7 Br2

This is an oxidation-reduction (redox) reaction:

14 Br-I - 14 e- 14 Br0 (oxidation)

4 Cr13/2 + 14 e- 4 CrIII (reduction)

Br- is a reducing agent, Cr2O7- is an oxidizing agent.

Reactants:

  • Cr2O7-
  • H3O+
    • Names: Hydronium source: wikidata, accessed: 2019-09-07, Hydroxonium source: wikidata, accessed: 2019-09-07, H3O(+) source: wikidata, accessed: 2019-09-07
  • Br-

Products:

  • Cr3+
  • 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
  • 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