Describe Preparation of NaOH at Laboratory

Preparation of NaOH:

In aqueous solution NaCI and water are dissociated as-

NaCI (aq) ↔ Na⁺ (aq) + Cl^– (aq)

H₂O (l) ↔ H⁺ (aq) + OH^– (aq)

When electricity is passed through the concentrated aqueous solution of NaCl then Na⁺ and H⁺ ion go to cathode electrode and since H⁺ has more reducing potential than Na⁺ and that is why it forms H₂ accepting electron from cathode. On the other side Cl^– & OH^– ions are drawn towards anode. Since Cl^– ion concentration is more than OH^– and hence left electron to the anode and forms Cl₂ gas.

Now the remaining OH^– and Na⁺ react to each other and form NaOH.

Na⁺ (aq) + OH^– (aq) — NaOH (aq)