Highlights
- Principle
- Extraction of aluminium
Electrochemical reactions
Key points
- Metal oxides undergo reduction in presence of carbon to become metals.
- They can undergo reduction thermodynamically and electrochemically.
- Reactive metals are difficult to be obtained by thermodynamic process.
- Delta G = change in Gibb’s free energy. Its negative value indicates the greater feasiblity of the reaction.
- E = cell emf. When it is positive, delta G becomes negative.
- Hall Herold extracted aluminium from its oxide in the molten form by electrochemical process.
| # | Item | Description |
| 1 | Electrolytic bath | Iron tank lined with carbon |
| 2 | Cathode | carbon lining |
| 3 | Anode | carbon blocks suspended in the bath |
| 4 | Electrolyte | 20% alumina, molten cryolite, 20% calcium chloride |
| 5 | Electrodic reaction | At cathode reduction occurs. At anode oxidation occurs. |