18.1.2—Describe
- Syllabus
- 9701–2028–2029
- Objective
- 18.1.2
- Level
- AS
Carboxylic acids react as weak acids and form esters
Carboxylic acids react with reactive metals to release H₂, with alkalis to form salt and water, and with carbonates to form salt, water and CO₂. With alcohols they esterify in concentrated sulfuric acid.
The same acid functional group supports different observations: gas evolution with metal/carbonate, neutralisation with alkali, and a reversible condensation with alcohol. Write the correct products for the reagent.
2CH₃COOH + 2Na → 2CH₃COONa + H₂; CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂. Ethanoic acid + ethanol ⇌ ethyl ethanoate + water.
A carboxylic acid is weak, not non-reactive; and esterification is not complete neutralisation because it is reversible.
ConceptA-Level CAIE Chemistry AS