Oxidation of Ethanol Simulation

🔬 Experiment Steps

Set up 50 mL round-bottom flask with 5 mL ethanol and magnetic stirrer
Heat to 40-50°C in water bath with stirring (under fume hood)
Add dilute acidified KMnO₄ (0.02M in H₂SO₄) dropwise while maintaining heat (40-50°C)
Continue heating while observing purple → colorless transition (MnO₄⁻ → Mn²⁺)
Add excess KMnO₄ at elevated temperature until persistent purple color indicates completion

⚗️ Chemical Reaction

5CH₃CH₂OH + 4KMnO₄ + 6H₂SO₄ → 5CH₃COOH + 4MnSO₄ + 2K₂SO₄ + 11H₂O

Ethanol is oxidized to acetic acid (CH₃COOH) by acidified potassium permanganate. The purple MnO₄⁻ is reduced to colorless Mn²⁺ ions. Acidic conditions provide better reaction control and higher yields.

KMnO₄ (Purple)
Mn²⁺ (Colorless in solution)
Observation: Purple KMnO₄ becomes colorless as it oxidizes ethanol to acetic acid. Purple color persists when excess oxidizing agent is added after complete oxidation.

💡 Why This Happens

Initial color disappearance: MnO₄⁻ (purple) is reduced to Mn²⁺ (colorless) as ethanol is oxidized to acetic acid under acidic conditions. Elevated temperature (40-50°C) improves reaction kinetics and ensures complete oxidation.

Color persistence with excess: When all ethanol is oxidized, additional KMnO₄ remains unreacted, maintaining purple color indicating reaction completion.

Temperature Control: The flask remains in the heated water bath throughout the reaction to maintain optimal conditions and control the exothermic oxidation process.

Safety Note: This reaction should be performed in a fume hood with proper ventilation due to heat generation and acid vapors.

⚠️ Laboratory Safety & Realism

Required Safety Equipment:

  • Fume hood for ventilation
  • Safety goggles and lab coat
  • Heat-resistant gloves
  • Emergency shower/eyewash access

Realistic Considerations:

  • Use round-bottom flask, not test tube
  • Magnetic stirring for proper mixing
  • Temperature monitoring (40-50°C)
  • Proper waste disposal procedures
  • Work with dilute solutions (0.02M KMnO₄)
Educational Note: This simulation shows idealized conditions. Real laboratory work requires additional safety measures and may produce different results due to impurities and side reactions.