Aluminum is extracted from aluminum oxide (Al₂O₃) using electrolysis. Here’s a explanation:
- Aluminum oxide is melted: It’s mixed with cryolite to lower its melting point and make it easier to melt.
- Electrolysis setup: The molten mixture is placed in an electrolytic cell with a positive electrode (anode) and a negative electrode (cathode).
- Electric current is passed through:
- At the cathode (negative), aluminum ions gain electrons and form aluminum metal.
- At the anode (positive), oxygen ions lose electrons and form oxygen gas.
- Collection of aluminum: The molten aluminum sinks to the bottom of the cell and is periodically removed.
Key points:
- Electrolysis is used because aluminum is too reactive to be reduced by carbon.
- Cryolite lowers the energy needed for the process.