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.