Final answer:
Alumina is extracted from the Hall-Heroult process by electrolyzing a molten mixture of aluminum oxide and cryolite at around 1000°C, producing molten aluminum and carbon dioxide.
Step-by-step explanation:
Alumina is extracted from the Hall-Heroult process through the electrolysis of a molten mixture containing approximately 5% aluminum oxide (Al₂O₃) and 95% cryolite (Na₃AlF₆). This mixture has a lower melting point than aluminum oxide alone. During electrolysis, which occurs at about 1000°C, molten aluminum is produced at the cathode, and carbon dioxide gas is released at the carbon anode. The overall chemical reaction can be summarized as:
2 Al₂O₃ (l) + 3 C(s) → 4 Al(l) + 3 CO₂ (g).
Prior to the electrolysis, the aluminum oxide is derived from the Bayer Process, which purifies bauxite to produce pure alumina.
The Hall-Heroult process is used to extract alumina from aluminum oxide. The process involves electrolyzing a molten mixture of about 5% aluminum oxide and 95% cryolite at about 1000°C. The electrolysis produces molten aluminum at the cathode and CO₂ gas at the carbon anode.