HClO4 (l) + 4 SO2 (aq) + 4 H2O (l) → 4 H2SO4 (aq) + HCl (aq)
This is an oxidation-reduction (redox) reaction:
4 SIV - 8 e- → 4 SVI (oxidation)
ClVII + 8 e- → Cl-I (reduction)
SO2 is a reducing agent, HClO4 is an oxidizing agent.
Reactants:
- HClO4 – Chloric(VII) acid
- 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.]
- H2O – Water, oxidane
Products:
- H2SO4 – Sulfuric acid
- HCl – Chlorane , Hydrogen chloride
- Other names: Hydrochloric acid , M , Uriatic acid
- Appearance: Colorless, transparent liquid, fumes in air if concentrated ; Colorless gas ; Colourless compressed liquefied gas with pungent odour ; Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.]