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.