what is electrolysis of water?

Electrolysis of water means passing electric current through water to decompose it into hydrogen gas and oxygen gas. The reaction that takes place during the process can be shown as:-

2H₂O → 2H₂ +O₂

Graphite rod acts as cathode and anode in water electrolysis.

Hydrogen and oxygen gases are collected at cathode and anode respectively.

At cathode:-

 Red

2 H⁺ _(aq) +2e^-  →  H₂

At anode:-

 Ox

OH^- _(aq)  →  OH + e^-

4 OH → 2H₂O + O₂