4.31C: Know that Ethanol can be Oxidised by: Burning in Air or Oxygen (Complete Combustion), Reaction with Oxygen in the Air to Form Ethanoic Acid (Microbial Oxidation), Heating with Potassium Dichromate (VI) in Dilute Sulfuric Acid to Form Ethanoic Acid

ETHANOL: C2H5OH                   OXIDATION: Loss of Electrons and gain of oxygen

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OXIDATION OF ETHANOL

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*COMPLETE COMBUSTION OF ETHANOL:

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• Ethanol can be oxidised by complete combustion when heated with an unlimited supply of Oxygen:

Ethanol    +    Oxygen    →    Carbon Dioxide    +    Water  C2H5OH              3O2                         2CO2                   3H2O

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*MICROBIAL OXIDATION:

• Microbial oxidation of Ethanol occurs when a bottle of wine is opened, causing bacteria in the air (Acetobacter) to use atmospheric Oxygen to oxidise Ethanol into a weak solution of Ethanoic acid:

Ethanol    +    Oxygen    →    Ethanoic Acid    +    Water  C2H5OH              3O2                    CH3COOH              3H2O

*Opened bottle of wine can quickly turn into vinegar due to the large number of Bacteria present in the air

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*HEATING WITH POTASSIUM DICHROMATE (VI) IN DILUTE SULFURIC ACID:
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• Ethanol can be oxidised by heating with an oxidising agent - such as Potassium Dichromate (VI) in Dilute Sulfuric Acid, causing orange solution containing Dichromate (VI) ions to be reduced into a green solution containing Chromium (II) ions: