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Do now!
Can you read through the blast furnace
equations?
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Last lessonThe reduction of
copper oxide using carbon.
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Extracting copper from copper oxide
2CuO + C 2Cu + CO2
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Today’s lesson
• The extraction of aluminium from aluminium oxide (Bauxite)
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Reactivity Series
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Electrolysis of aluminium oxide
CO2
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Electrolysis of aluminium oxide
Aluminium oxide has a high melting point (2054°C) (EXPENSIVE)
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Electrolysis of aluminium oxide
Aluminium oxide will dissolve in molten cryolite which melts at “only” 959°C (CHEAPER)
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Electrolysis of aluminium oxide
The molten liquid is put into a large chamber, the walls of which are connected to the negative side of a circuit (cathode). Large positive electrodes (anodes) made of graphite are lowered into the mixture.
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Electrolysis of aluminium oxide
Aluminum oxide is an ionic compound. The positive aluminium ions drift to the negative electrode (cathode) and the negative oxygen ions to the positive electrodes (anodes).
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Electrolysis of aluminium oxide
At the cathode the aluminium ions gain electrons and become aluminium atoms.
4Al3+ + 12e- 4Al
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Electrolysis of aluminium oxide
At the anodes the oxygen ions lose electrons and become oxygen atoms.
6O2- 3O2 + 12e-
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Electrolysis of aluminium oxide
The oxygen immediately reacts with the hot graphite to form carbon dioxide. This means the graphite electrodes have to be replaced occasionally as they wear away.
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Electrolysis of aluminium oxide
Molten aluminium is tapped from the bottom of the chamber
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Electrolysis of aluminium oxide
This all requires LOTS of electricity so is an expensive process.
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Electrolysis of Aluminium• Aluminium oxide has a high melting point (2054°C) (EXPENSIVE)• Aluminium oxide will dissolve in molten cryolite which melts at “only” 959°C
(CHEAPER)• The molten liquid is put into a large chamber, the walls of which are connected to the
negative side of a circuit (cathode). Large positive electrodes (anodes) made of graphite are lowered into the mixture.
• Aluminum oxide is an ionic compound. The positive aluminium ions drift to the negative electrode (cathode) and the negative oxygen ions to the positive electrodes (anodes).
• At the cathode the aluminium ions gain electrons and become aluminium atoms.4Al 3+ + 12e- 4Al
• At the anodes the oxygen ions lose electrons and become oxygen atoms.6O2- 3O2 + 12e-
• The oxygen immediately reacts with the hot graphite to form carbon dioxide. This means the graphite electrodes have to be replaced occasionally as they wear away.
• Molten aluminium is tapped from the bottom of the chamber
Maximum two words per drawing - numbers allowed
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Homework
Can you complete the “Draw the
sentence” exercise for Wednesday 23rd
September?