Ethanol can be oxidised to form ethanoic acid. Describe what happens during the oxidation of ethanol, name the type of product formed, and explain why this process is an example of oxidation.

Edexcel A-Level Chemistry (9CH0) — 6.5 Alcohols and oxidation · Describe · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Ethanol (C₂H₅OH) is a common alcohol. When left exposed to air in the presence of bacteria, or when treated with an oxidising agent, ethanol undergoes a chemical change to produce a compound with the molecular formula CH₃COOH.

Model answer (5 marks)

Ethanol is oxidised by gaining oxygen atoms.
1. The –OH group of ethanol is oxidised to a –C(=O)OH group.
2. The product is ethanoic acid, a carboxylic acid.
3. Oxidation is a reaction in which a substance gains oxygen.
4. In this case ethanol gains oxygen, so the reaction is an oxidation.
5. An oxidising agent (oxygen from air or a chemical oxidiser) supplies the oxygen.

Examiner tips

  • Use the word "gains oxygen" to show oxidation. Mention the product as ethanoic acid/carboxylic acid. Explain the definition of oxidation. State the oxidising agent.
  • common_mistakes
  • :
  • Saying ethanol loses oxygen instead of gains. Calling the product a ketone or aldehyde. Omitting the oxidising agent or the definition of oxidation.

Mark scheme (5 marks)

  1. Ethanol gains oxygen (during the reaction)
  2. The product formed is ethanoic acid / a carboxylic acid
  3. Oxidation is defined as a reaction involving the gain of oxygen
  4. Ethanol has gained oxygen in this reaction, so it fits the definition of oxidation
  5. An oxidising agent / oxygen (from air or oxidising agent) is required to carry out this oxidation

Key terms in this question

oxidation · ethanol · ethanoic acid

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