Hall-Héroult Process (Aluminum Smelting)
2Al2O3 + 3C → 4Al + 3CO2
Overview
Alumina (Al₂O₃) is dissolved in molten cryolite (Na₃AlF₆) at 960°C and electrolyzed using carbon anodes. Aluminum is deposited at the cathode and oxygen reacts with the carbon anode to form CO₂. Independently invented by Charles Hall and Paul Héroult in 1886, this process reduced aluminum from a precious metal to a commodity.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Aluminum Oxide Al₂O₃ | 2 | (l) |
| Reactant | Carbon C | 3 | (s) |
| Product | Carbon Dioxide CO₂ | 3 | (g) |
| Product | Aluminum Al | 4 | (l) |
Everyday Example
Every piece of aluminum foil, beverage can, and airplane wing was produced by the Hall-Héroult process.
Industrial Importance
Aluminum smelting produces 65 million tonnes annually and consumes about 3% of global electricity. Recycling uses only 5% of the energy.
Properties
- Type
- Electrochemical
- Reversible
- No
- Energy
- Endothermic
- ΔH
- 2168.0 kJ/mol
- Catalyst
- Cryolite (Na₃AlF₆) solvent
Related Reactions
Alkaline Battery Discharge
Anodizing of Aluminum
Cathodic Protection (Zinc Sacrificial Anode)
Chlor-Alkali Electrolysis
Chrome Electroplating
Copper Electroplating
Daniell Cell (Zinc-Copper Galvanic Cell)
Electrochemical CO₂ Reduction to CO
Electrochemical Machining (ECM)
Electrolysis of Molten NaCl (Downs Process)
Frequently Asked Questions
What is the equation for Hall-Héroult Process (Aluminum Smelting)?
The balanced equation is: 2Al₂O₃ + 3C → 4Al + 3CO₂.
What type of reaction is Hall-Héroult Process (Aluminum Smelting)?
Hall-Héroult Process (Aluminum Smelting) is a electrochemical reaction.
Is Hall-Héroult Process (Aluminum Smelting) exothermic or endothermic?
Hall-Héroult Process (Aluminum Smelting) is endothermic (absorbs energy). The enthalpy change (ΔH) is 2168.0 kJ/mol.
What conditions are needed for Hall-Héroult Process (Aluminum Smelting)?
This reaction requires a catalyst (Cryolite (Na₃AlF₆) solvent).