Cr2O72- + 2 H+ + 3 SO2 → 2 (Cr)3+ + 3 SO42- + H2O
This is an oxidation-reduction (redox) reaction:
3 SIV - 6 e- → 3 SVI (oxidation)
2 CrVI + 6 e- → 2 CrIII (reduction)
SO2 is a reducing agent, Cr2O72- is an oxidizing agent.
- SO2 – Sulfur dioxide
- Other names: Sulfurous anhydride , Sulphur dioxide , Sulfurous acid anhydride
- Appearance: Colorless gas ; Colourless gas or compressed liquefied gas with pungent odour ; Colorless gas with a characteristic, irritating, pungent odor. [Note: A liquid below 14°F. Shipped as a liquefied compressed gas.]