Dichromate Oxidation of Ethanol
2Cr2O72− + 3C2H5OH + 16H+ → 4Cr3+ + 3CH3COOH + 11H2O
Overview
Potassium dichromate oxidizes ethanol to acetic acid in acidic solution. Chromium(VI) is reduced to chromium(III), changing color from orange to green. The ethanol is oxidized through acetaldehyde to acetic acid. This color change was the basis of early breathalyzer tests.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Ethanol C₂H₅OH | 3 | (aq) |
| Product | Acetic Acid CH₃COOH | 3 | (aq) |
| Product | Water H₂O | 11 | (l) |
Everyday Example
Early police breathalyzer devices (Breathalyzer tubes) used this reaction, where the orange-to-green color change indicated blood alcohol level.
Industrial Importance
Dichromate oxidation was historically important in organic synthesis. Modern practice avoids Cr(VI) due to carcinogenicity, replacing it with catalytic or enzymatic methods.
Properties
- Type
- Redox
- Reversible
- No
- Energy
- Exothermic
- ΔH
- -1920.0 kJ/mol
Related Reactions
Aqua Regia Dissolving Gold
Bleaching with Sodium Hypochlorite
Cerium(IV) Reduction by Iron(II)
Chlorine Oxidation of Bromide
Chromate-Dichromate Equilibrium
Contact Process SO₂ Oxidation
Copper Displaced by Iron
Copper Oxidation by Nitric Acid
Copper Patina Formation (Verdigris)
Copper Reduction of Silver Ion
Frequently Asked Questions
What is the equation for Dichromate Oxidation of Ethanol?
The balanced equation is: 2Cr₂O₇²⁻ + 3C₂H₅OH + 16H⁺ → 4Cr³⁺ + 3CH₃COOH + 11H₂O.
What type of reaction is Dichromate Oxidation of Ethanol?
Dichromate Oxidation of Ethanol is a redox reaction.
Is Dichromate Oxidation of Ethanol exothermic or endothermic?
Dichromate Oxidation of Ethanol is exothermic (releases energy). The enthalpy change (ΔH) is -1920.0 kJ/mol.