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IGCSEChemistryEdexcelChemistry (Modular)Unit 2Revision Notes8 Organic chemistry: Part 2Carboxylic acidsWhat are Carboxylic Acids?

What are Carboxylic Acids? (Edexcel IGCSE Chemistry (Modular)): Revision Note

Alexandra Brennan

Written by: Alexandra Brennan

Reviewed by: Stewart Hird

Updated on

Edexcel Chemistry (Modular): Unit 2Edexcel Chemistry

Carboxylic acids

  • Carboxylic acids is the name given to compounds containing the functional group carboxyl, -COOH

  • The general formula of a carboxylic acid is CnH2n+1COOH which can be shortened to just RCOOH

Carboxylic acid functional group

Diagram of the general structure of a carboxylic acid

Diagram of the general structure of a carboxylic acid. The R- represents a varying hydrocarbon chain

  • The naming of a carboxylic acid follows the pattern alkan + oic acid

  • The names and structure of the first four carboxylic acids are shown below

  • Vinegar is an aqueous solution of ethanoic acid and contains about 5% of the acid by volume.

Diagram showing the displayed formula of the first four carboxylic acids

The structures and formulae of the first four carboxylic acids

  • The formula for each carboxylic acid is:

    • Methanoic acid- HCOOH

    • Ethanoic acid- CH3COOH

    • Propanoic acid- CH3CH2COOH

    • Butanoic acid- CH3CH2CH2COOH

Examiner Tips and Tricks

The carbon atom in the -COOH functional group is counted as part of the molecule and not just the functional group. E.g. CH3CH2CH2COOH has 4 carbon atoms so is called butanoic acid, not propanoic acid.

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    Author
    Reviewer
    Alexandra Brennan

    Author: Alexandra Brennan

    Expertise: Chemistry Content Creator

    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

    Reviewer: Stewart Hird

    Expertise: Chemistry Content Creator

    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.