Specification Point 4.31C (Paper 2C Only):
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: The loss of electrons and gain in oxygen.

Oxidation of Ethanol

*complete combustion of ethanol:

Ethanol can be oxidised by the process of complete combustion as ethanol burns when heated in air or oxygen:

Ethanol    +    Oxygen    →    Carbon dioxide    +    water

 C2H5OH              3O2                         2CO2                   3H2O

*microbial oxidation:

  • The microbial oxidation of ethanol occurs once a bottle of wine is opened.
  • This is caused by the bacteria in the air (acetobacter) using atmospheric oxygen from air to oxidise the ethanol in wine, producing a weak solution of ethanoic acid (also known as acetic acid):

Ethanol    +    Oxygen    →    Ethanoic Acid    +    Water

 C2H5OH              3O2                    CH3COOH              3H2O

So once a bottle of wine has been opened, it can quickly turn into vinegar due to the large number of bacteria in the air.

*Heating with potassium dichromate (vi) in dilute Sulfuric acid:

  • Ethanol can be oxidised by heating it with an oxidising agent such as Potassium dichromate (vi) in dilute Sulphuric acid.
  • The alcohol is oxidized to a carboxylic acid.
  • If the oxidation occurs, then the orange solution containing the dichromate (vi) ions is reduced to a green solution containing chromium (ii) ions:
Ethanol oxidised, Edexcel IGCSE Chemistry

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.