Name: Uses of Hydrogen
Uploaded: 2019-07-19
Duration: 3 min 14 s
Description: We know about the physical and chemical properties of hydrogen and its production process. Let's learn about its uses in welding, production of ammonia, and...

Question

How is hydrogen prepared by electrolysis? What are the reactions that take place at the anode and cathode?

Accepted Answer

Hydrogen can also be prepared by the electrolysis of water. Electrolysis is the process by which a compound dissociates or splits into ions when an electric current is passed through it. During the electrolysis of water, water decomposes into hydrogen and oxygen. As pure water is a non-electrolyte, acidified water, or water to which dilute sulphuric acid is added, is used to make it a good conductor. Oxygen gas is evolved at the anode and hydrogen at the cathode.

Since two molecules of hydrogen are produced for each molecule of oxygen, the volume of hydrogen gas released will be twice that of the volume of oxygen gas formed.

At cathode: $2 H^{+} + 2 e^{-} \to H_{2}$

At anode: $2 H_{2} O \to O_{2} + 4 H^{+} + 4 e^{-}$

The net reaction is written as $2 H_{2} O \to O_{2} + 2 H_{2}$

How is hydrogen prepared by electrolysis? What are the reactions that take place at the anode and cathode?

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