Chlor-Alkali Electrolysis

2NaCl + 2H2O → Cl2 + 2NaOH + H2

Overview

Electrolysis of concentrated brine (NaCl solution) produces three essential industrial chemicals simultaneously: chlorine gas at the anode, sodium hydroxide solution at the cathode, and hydrogen gas as a byproduct. Modern membrane cells use ion-exchange membranes to separate products and achieve 95%+ current efficiency.

Participants

Role Substance Coefficient State
Reactant Sodium Chloride NaCl 2 (aq)
Reactant Water H₂O 2 (l)
Product Sodium Hydroxide NaOH 2 (aq)

Everyday Example

The chlorine in your tap water and the lye in drain cleaner both come from this single electrochemical process.

Industrial Importance

The chlor-alkali industry produces about 75 million tonnes of NaOH and 65 million tonnes of Cl₂ annually, consuming about 1% of global electricity.

Properties

Type
Electrochemical
Reversible
No
Energy
Endothermic
ΔH
422.0 kJ/mol

Related Reactions

Alkaline Battery Discharge Anodizing of Aluminum Cathodic Protection (Zinc Sacrificial Anode) Chrome Electroplating Copper Electroplating Daniell Cell (Zinc-Copper Galvanic Cell) Electrochemical CO₂ Reduction to CO Electrochemical Machining (ECM) Electrolysis of Molten NaCl (Downs Process) Electrolysis of Water

Frequently Asked Questions

What is the equation for Chlor-Alkali Electrolysis?
The balanced equation is: 2NaCl + 2H₂O → Cl₂ + 2NaOH + H₂.
What type of reaction is Chlor-Alkali Electrolysis?
Chlor-Alkali Electrolysis is a electrochemical reaction.
Is Chlor-Alkali Electrolysis exothermic or endothermic?
Chlor-Alkali Electrolysis is endothermic (absorbs energy). The enthalpy change (ΔH) is 422.0 kJ/mol.