Question

Explain hydrolysis, i.e, what types of molecules undergo hydrolysis (be specific) and show equations for reactions of acid, base, and salt hydrolysis not used as examples in the introduction to this experiment.

Answer 1

Hydrolysis:

The reaction which involves breaking of bond using water molecule is called as hydrolysis.

Broadly we have three types of hydrolysis.

Salt Hydrolysis:

This is by adding common salt to water to make salt solution.

E.g. NaCl the bond between Na⁺ and Cl^- breaks and it becomes solution of ions Na⁺ and Cl^-.

NaCl_(s) -> Na⁺_(aq) + Cl^-_(aq)

These Na⁺ ions are stabilised by OH^- ions which are formed by dissociation of H₂O, and Cl^- ions are stabilized by H⁺ ions which are formed by dissociation of H₂O.

Each of these ions are conjugate strong acid-base pairs.

When salt is of strong acid base (NaCl), then the aquious Solution formed is neutral.

When salt is of Strong acid, weak base (NH₄Cl) solution formed is acidic.

And when salt is of weak acid, strong base (CH₃COONa) solution formed is basic.

Acid Hydrolysis:

When acid is added to the water, water act as a base which can abstract proton from acid to give solution of H₃O⁺ and conjugate base.

CH₃COOH_(l) + H₂O_(l) -> CH₃COO^-_(aq) + H₃O⁺_(aq)

Base Hydrolysis:

When base is added to the water, water act as an acid which gives proton to form OH^- ion and conjugate acid.

NH_3(g) + H₂O_(l) -> NH⁴⁺_(aq) + OH^-_(aq)