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)