Carboxylic Acids (OCR GCSE Chemistry A (Gateway)): Revision Note

Carboxylic Acids Structure & Formula

• Carboxylic acids are a homologous series of compounds that have the general formula of

C_nH_2n+1 COOH 

• They differ by one -CH₂ in the molecular formulae from one member to the next

• They show a gradation in their physical properties:

  • Boiling points increase with increased carbon chain length

  • Viscosity increases with increased carbon chain length

• They have similar chemical properties

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

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

• In terms of naming, the same system is used as for alkanes and alkenes, with the final ‘e’ being replaced with ‘oic’ and then the word acid

The structures and formulae of the first four carboxylic acids