1. Can you think of some uses for aluminium?
Do now!
Can you think of some uses for aluminium?
Iron nipples

2. Last lesson
The extraction of aluminium from aluminium oxide (Bauxite)

3. Reactivity Series 3

4. Electrolysis of aluminium oxide
CO2

5. Electrolysis of aluminium oxide
Aluminium oxide has a high melting point (2054°C) (EXPENSIVE)

6. Electrolysis of aluminium oxide
Aluminium oxide will dissolve in molten cryolite which melts at “only” 959°C (CHEAPER)

7. 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.

8. 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).

9. Electrolysis of aluminium oxide
At the cathode the aluminium ions gain electrons and become aluminium atoms.
4Al e- 4Al

10. Electrolysis of aluminium oxide
At the anodes the oxygen ions lose electrons and become oxygen atoms.
6O2- 3O2 + 12e-

11. 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.

12. Electrolysis of aluminium oxide
Molten aluminium is tapped from the bottom of the chamber

13. Electrolysis of aluminium oxide
This all requires LOTS of electricity so is an expensive process.

14. Electrolysis of Aluminium
Maximum two words per drawing - numbers allowed
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 e- 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

15. A sheet!

16. Today’s lesson
Extraction of Zinc using electrolysis and by heating with carbon
Extraction of Chromium using the thermite process

17. Zinc

18. I’m mainly Zinc Sulphide ZnS (s)
Zinc blende
I’m mainly Zinc Sulphide ZnS (s)

19. I’m mainly Zinc Sulphide ZnS (s)
Zinc blende
Roasted in air to make zinc oxide
2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO 2(g)

20. I’m mainly Zinc Sulphide ZnS (s)
Zinc blende
Roasted in air to make zinc oxide
2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO 2(g)
Zinc oxide reduced by carbon monoxide in a furnace
2ZnO(s) + CO(g) Zn(s) + CO2(g)

21. I’m mainly Zinc Sulphide ZnS (s)
Zinc blende
Roasted in air to make zinc oxide
2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO 2(g)
Zinc oxide reduced by carbon monoxide in a furnace
2ZnO(s) + CO(g) Zn(s) + CO2(g)
Copy please!

22. Another way of separating the zinc in zinc oxide

23. Another way of separating the zinc in zinc oxide
React the zinc oxide (a base) with sulphuric acid to make zinc sulphate
H2SO4(aq) + ZnO(s) ZnSO4(aq) + H2O(l)

24. Another way of separating the zinc in zinc oxide
React the zinc oxide (a base) with sulphuric acid to make zinc sulphate
H2SO4(aq) + ZnO(s) ZnSO4(aq) + H2O(l)
The solution is then electrolysed giving zinc at the cathode
Zn2+(aq) + 2e- Zn(s)

25. Another way of separating the zinc in zinc oxide
React the zinc oxide (a base) with sulphuric acid to make zinc sulphate
H2SO4(aq) + ZnO(s) ZnSO4(aq) + H2O(l)
The solution is then electrolysed giving zinc at the cathode
Zn2+(aq) + 2e- Zn(s)
Copy please!

26. Extraction of chromium

27. Extraction of chromium
Another “Thermite” reaction
Cr2O3(s) + 2Al(s) Al2O3(s) + 2Cr(s)
YouTube - New Improved Chromium thermite

28. Extraction of chromium
Another “Thermite” reaction
Cr2O3(s) + 2Al(s) Al2O3(s) + 2Cr(s)
You guessed it!
YouTube - New Improved Chromium thermite

29. Let’s watch something fun

30. Moles!