Question

Which of the following salts will have the highest pH in water?

(a) KCl
(b) NaCl
(c) Na₂CO₃
(d) CuSO₄

Answer 1

(c) Na₂CO₃

KCl and NaCl, being salts of strong acid and strong base do not get hydrolysed. Their aqueous solutions are neutral and hence their pH = 7.

Na₂CO₃ being a salt of weak acid and a strong base, gives NaOH as a product of hydrolysis. Hence, its aqueous solution is alkaline and has pH >7.

CuSO₄ being a salt of strong acid and weak base, gives H₂SO₄, as a product of hydrolysis H₂SO₄ is a strong acid and its pH < 7.