We know that the volume of hydrogen and oxygen in electrolysis of water is 2:1, but we see in ncert text book that there is more amount of water in anode than cathode , what is the reason behind this contradiction

Asked by saradamahapatra9999 | 5th Apr, 2020, 03:33: PM

Expert Answer:

let's study electrolysis of water in detail:

Electrolysis of Acidified Water

Electrolyte: Acidified water


Anode: Platinum

Cathode: Platinum

Ionisation of acidified water: H2O  → H+ + OH

                                              H2SO4  → 2H+ + SO42–

Ions present: H+, SO42–, OH

Electrode reactions: 

Reaction at the cathode: H+ + e → H

                                         H + H → H2 (hydrogen molecule)

Reaction at the anode: OH − e  → OH × 4

OH– ion discharge in preference to SO42–

                  4OH → 2H2O + O2 (oxygen molecule) 

At the cathode, Hydrogen gas is evolved and at the anode, oxygen gas is liberated.

The water molecule has two atoms of hydrogen and one atom of oxygen, that means in the no. of hydrogens are double than that of oxygen,

hence the amount of hydrogen gas evolved collected in one of the test tubes doubles the amount in the other gas i.e., oxygen.

Answered by Ramandeep | 5th Apr, 2020, 08:05: PM