6.3 The extraction of aluminium
No description yet. This curated deck is ready for daily study.
Card preview (11)
What are the uses of alluminium
• pans • cooking foil • drink cans
Where can you get aluminium oxide from
ore called bauxite
Explain why aluminium cannot be extracted from its oxide by reduction with carbon
Carbon is not reactive enough to use in its extraction so cannot displace aluminium
Explain why cryolite is added
Reduces overall melting point and energy needed
Explain why the carbon electrodes must be replaced frequently
oxygen reacts with hot carbon anodes making carbon dioxide, so carbon anodes gradually burn away, needing to be replaced regularly
Give two reasons why the extraction of aluminium is expensive
High melting point requires a lot of energy, replacing positive electrodes
Write half equations for the reactions at the anode and cathode, and if they are oxidiation or reduction, for the extraction of aluminium
Anode: 2O²- -> 0₂ + 4e- Oxidation Cathode A³+ + 3e- -> Al Reduction
Name the compound from which aluminium is extracted
bauxite
What are the steps for extracting aluminium?
• mine bauxite ore by open cast mining • separate aluminium oxide from ore • extract aluminium by electrolysis
What does bauxite contain other than aluminium oxide
• iron oxide • makes waste solution from separations rusty brown colour • wastewater stored in large lagoons
How do scientists lower the boiling point of aluminium
mix it with cryolite (another ionic compound)