Question

Consider the following salts:

Na₂CO₃, NaCl, NH₄Cl, CH₃COONa, K₂SO₄, (NH)₂SO₄

Which of these salts will give:

1. acidic solutions?
2. neutral solutions?
3. basic solutions (or alkaline solutions)?

Answer 1

1. The salt solutions of NH₄Cl and (NH₄)₂SO₄ are acidic because each salt is formed from a weak base and a strong acid. The ionisation of a weak base is not complete, whereas a strong acid ionises completely. Hence, there are more H⁺ ions than OH⁻  ions, making the solutions acidic.
2. The salt solutions of NaCl and K₂SO₄ are neutral, because these salts are formed from a strong base and a strong acid, and on ionisation, there is an equal number of H⁺ and OH⁻ ions, making the solutions neutral.
3. The salt solutions of CH₃COONa and Na₂CO₃ are basic because these salts are each formed from a weak acid and a strong base. The ionisation of a weak acid is not complete, whereas a strong base ionises completely. Hence, there are more OH⁻ ions than H⁺ ions, making the solutions basic.