Question

In which of the following salts would both the positive ion and the negative ion hydrolize when the salt is dissolved in water?

A. NaCl B. NaCN C. NH4Cl

Answer 1

Hydrolysis of salt is the reaction where one of the ions from the salt react with the water to form either acidic or basic solution.

a) NaCl ----> Na⁺ + Cl^-

NaCl is a salt of strong base and strong acid and the solution contain equal number of hydrogen ions and hydroxide ions. Hence solution remain neutral.

b) NaCN ---> Na⁺ + CN^-

CN^- + H₂O ---> HCN + OH^-

NaCN is a salt of strong base and weak acid and the anion (negative ion) undergo hydrolysis to form a weak acid and hydroxide ions. As the hydroxide ions are produced this makes the solution basic/alkaline in nature.

c) NH₄Cl ---> NH₄⁺ + Cl^-

NH₄⁺ + H₂O ----> NH₄OH + H⁺

NH₄Cl is a salt of weak base and strong acid. The cation (positive charge) that undergo hydrolysis to form weak base and hydrogen protons. As the protons are produced this makes the solution acidic in nature.