Carboxylic Acids (Cambridge (CIE) IGCSE Chemistry): Revision Note

Carboxylic acids

• The carboxylic acids behave like other acids

• They react with:

  • metals to form a salt and hydrogen

  • carbonates to form a salt, water and carbon dioxide gas

  • bases to form a salt and water

• The salts formed by the reaction of carboxylic acids all end –anoate

• So methanoic acid forms a salt called methanoate, ethanoic a salt called ethanoate etc.

• In the reaction with metals, a metal salt and hydrogen gas are produced

Example reactions of carboxylic acids 

• The reaction of ethanoic acid with metals such as magnesium forms the salt magnesium ethanoate and hydrogen gas: 

2CH₃COOH + Mg → (CH₃COO)₂Mg + H₂

• The neutralisation reaction of a carboxylic acid with a hydroxide produces salt and water

• For example, the reaction between potassium hydroxide and ethanoic acid forms the salt potassium ethanoate and water: 

CH₃COOH + KOH → CH₃COOK + H₂O

• The reaction of a carboxylic acid with a carbonate produces a metal salt, water and carbon dioxide

• For example, in the reaction between potassium carbonate and ethanoic acid, the salt potassium ethanoate is formed with water and carbon dioxide

2CH₃COOH + K₂CO₃ → 2CH₃COOK + H₂O + CO₂