Decomposition of Water (Electrolysis)

2H2O → 2H2 + O2

Overview

Water decomposes into hydrogen and oxygen gases when an electric current is passed through it. This electrolysis reaction is the reverse of the synthesis of water. It requires a minimum voltage of 1.23 V at standard conditions, though practical electrolyzers use higher voltages.

Participants

Role Substance Coefficient State
Reactant Water H₂O 2 (l)
Product Oxygen O 1 (g)
Product Hydrogen H 2 (g)

Everyday Example

Green hydrogen production uses renewable electricity to split water, producing clean hydrogen fuel for vehicles and industry.

Industrial Importance

Water electrolysis is central to the green hydrogen economy, producing hydrogen for fuel cells, ammonia synthesis, and steel production without carbon emissions.

Properties

Type
Decomposition
Reversible
Yes
Energy
Endothermic
ΔH
571.6 kJ/mol

Related Reactions

Cracking of Octane (Thermal Cracking) Decomposition of Ammonium Nitrate Decomposition of Barium Peroxide Decomposition of Calcium Carbonate (Calcination) Decomposition of Calcium Hypochlorite Decomposition of Carbonic Acid Decomposition of Hydrogen Peroxide Decomposition of Iron(II,III) Oxide (Direct Reduction) Decomposition of Nitroglycerin Decomposition of Nitrous Oxide (Laughing Gas)

Frequently Asked Questions

What is the equation for Decomposition of Water (Electrolysis)?
The balanced equation is: 2H₂O → 2H₂ + O₂.
What type of reaction is Decomposition of Water (Electrolysis)?
Decomposition of Water (Electrolysis) is a decomposition reaction. It is reversible under certain conditions.
Is Decomposition of Water (Electrolysis) exothermic or endothermic?
Decomposition of Water (Electrolysis) is endothermic (absorbs energy). The enthalpy change (ΔH) is 571.6 kJ/mol.