Carboxylic Acid


  • Functional group: carboxyl group, \(-COOH\)
  • General formula: \(C_nH_{2n+1}COOH\)


Naming carboxylic acid

  • Replacing the ‘ol’ at the end of alcohol name with ‘oic acid’.
  • Example: methanol to methanoic acid.


Steps in naming a carboxylic acid

  1. Determine the name of the main chain based on the number of carbon atoms in the longest and continuous carbon chain.
  2. The numbering of the longest carbon chain starts from the carboxyl group.
  3. Determine the position of the branch chain. 
Example: Structural formula for 3,4-dimethylhexanoic acid


Physical properties of ethanoic acid

  • A colourless solution at room temperature
  • Have a sour smell
  • Boiling point: 118°C
  • Volatile
  • Soluble in water


Uses of carboxylic acid

  • Fruits and vegetables contain carboxylic acid.
    • Orange has citric acid.
  • Milk becomes sour because of the lactic acid formed.
  • Used in daily life items;
    • Cosmetics
    • Liquid detergent
  • Used in the food industry;
    • Food flavouring
    • Food preservatives