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Do now!

Do now!. Can you think of some uses for aluminium?. Iron nipples. Last lesson. The extraction of aluminium from aluminium oxide (Bauxite). Reactivity Series. Electrolysis of aluminium oxide. CO 2. Electrolysis of aluminium oxide.

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Do now!

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  1. 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

  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. 4Al3+ + 12e- 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. 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 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

  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. 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!

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