Oxidation of Ethanol (Edexcel IGCSE Chemistry (Modular))

Revision Note

Test yourself

Oxidation of ethanol

  • Ethanol can undergo oxidation in three different ways:

    • Combustion (burning in air)

    • Aerobic oxidation

    • Treatment with an oxidising agent

Combustion

  • Alcohols undergo combustion to form carbon dioxide and water

  • The complete combustion of ethanol is as follows:

    Equation to show the complete combustion of ethanol
  • Ethanol burns readily with an almost invisible blue flame

  • School laboratories use ethanol in spirit burners as it burns cleanly and without strong odours

Aerobic Oxidation

  • Bacteria in the air (acetobacter) use oxygen from the air to oxidise the ethanol in the wine:

ethanol + oxygen → ethanoic acid + water

  • The acidic, vinegary taste of wine which has been left open for several days is due to the presence of ethanoic acid

  • This is what happens to wine when it is left open as the microbial oxidation of ethanol will produce a weak solution of the carboxylic acid, ethanoic acid, the same acid used in vinegar

Treatment with an oxidising agent

  • Alcohols undergo oxidation to produce carboxylic acids when treated with oxidising agents

  • When ethanol is heated with  potassium dichromate(VI) solution in sulfuric acid, the ethanol oxidises to ethanoic acid

  • The equation for the reaction is:

CH3CH2OH + [O]  →  CH3COOH + H2O

  • The oxidising agent is represented by the symbol for oxygen in square brackets

  • The reaction is slow so the mixture is heated to its boiling point for about an hour; to avoid the substances evaporating a condenser is placed above the reaction flask that prevents volatile liquids from escaping

  • During the reaction the potassium dichromate turns from orange to green

The oxidation of ethanol

Equipment showing ethanol being heated under reflux

Ethanol can be oxidised by heating it with potassium dichromate in sulfuric acid. The solution turns  from orange to green during the reaction

Examiner Tip

Be careful when writing the equation for the combustion of ethanol- students often forget to include the oxygen in the ethanol when balancing the equation.

Last updated:

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Alexandra Brennan

Author: Alexandra Brennan

Expertise: Chemistry

Alex studied Biochemistry at Newcastle University before embarking upon a career in teaching. With nearly 10 years of teaching experience, Alex has had several roles including Chemistry/Science Teacher, Head of Science and Examiner for AQA and Edexcel. Alex’s passion for creating engaging content that enables students to succeed in exams drove her to pursue a career outside of the classroom at SME.

Stewart Hird

Author: Stewart Hird

Expertise: Chemistry Lead

Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Topic Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.