Download - Making aluminium
Making aluminium
Keywords and big picture starter
• Bauxite, Aluminium oxide, graphite, cryolite, electricity, molten, malleable, strong, low density and unreactive.
• Take a look at the bauxite ore and aluminium foil shown on the desk
think of 5 facts and uses about aluminiumUse the keywords above to help
THE ELECTROLYSIS OF ALUMINIUM FROM ALUMINIUM OXIDE
• L.O. Explain with diagrams – the extraction of aluminium from bauxite
• Evaluate the importance of conditions needed for extraction of aluminium
Explain with diagrams – the extraction of aluminium from bauxite
1. What do the red, grey and black areas represent?2. What do the yellow areas represent?3. What is being oxidised? 4. What is being reduced? 5. Which way will electrons flow and why?6. How can you summarise this process using half equations
Add as much detail to the picture of this electrolytic cell to explain how aluminiumis extracted
Explain with diagrams – the extraction of aluminium from bauxite1. What do the red, grey and black areas represent?2. What do the yellow areas represent?3. What is being oxidised? 4. What is being reduced? 5. Which way will electrons flow and why?6. How can you summarise this process using half equations
start
EXTRACTION OF ALUMINIUM
THE CELL CONSISTS OF A
Help 1
EXTRACTION OF ALUMINIUM
CARBON ANODE
THE CELL CONSISTS OF A CARBON ANODE
Help 2
EXTRACTION OF ALUMINIUM
STEEL CATHODECARBON LINING
THE CELL CONSISTS OF A CARBON LINED STEEL CATHODE (iron and carbon)
Help 3
EXTRACTION OF ALUMINIUM
MOLTEN ALUMINA and
CRYOLITE
ALUMINA IS DISSOLVED IN MOLTEN CRYOLITE Na3AlF6
SAVES ENERGY - the mixture melts at a lower temperature
Help 4
EXTRACTION OF ALUMINIUM
MOLTEN ALUMINA and
CRYOLITE
ALUMINA IS DISSOLVED IN MOLTEN CRYOLITE Na3AlF6
aluminium and oxide ions are now free to move
Help 5
EXTRACTION OF ALUMINIUM
POSITIVE ALUMINIUM IONS ARE ATTRACTED
TO THE NEGATIVE CATHODE
Al3+ + 3e- AlEACH ION PICKS UP 3 ELECTRONS AND IS DISCHARGED
CARBON CATHODE
Help 6
O2- O + 2e-
EXTRACTION OF ALUMINIUM
NEGATIVE OXIDE IONS ARE
ATTRACTED TO THE POSITIVE
ANODE
EACH ION GIVES UP 2 ELECTRONS AND IS DISCHARGED
CARBON ANODE
Help 7
EXTRACTION OF ALUMINIUM
ELECTRONS
CARBON ANODE
CARBON CATHODE
Electrons will flow from most reactive to least
reactive electrode
Help 8
EXTRACTION OF ALUMINIUM
ELECTRONS
ANODE OXIDATION
OXIDATION (LOSS OF ELECTRONS) TAKES PLACE
AT THE ANODECARBON ANODE
Help 9
EXTRACTION OF ALUMINIUM
ELECTRONS
CATHODE REDUCTION
OXIDATION (LOSS OF ELECTRONS) TAKES PLACE
AT THE ANODE
REDUCTION (GAIN OF ELECTRONS) TAKES PLACE AT
THE CATHODE CARBON CATHODE
ANODE OXIDATION
Help10
ELECTRONSOXIDATION (LOSS OF ELECTRONS) TAKES PLACE
AT THE ANODE
REDUCTION (GAIN OF ELECTRONS) TAKES PLACE AT
THE CATHODE
CARBON ANODE
CARBON CATHODE
ANODE 2O2- O2 + 4e- OXIDATION CATHODE Al3+ + 3e- Al REDUCTION
ALUMINA IS DISSOLVED IN MOLTEN CRYOLITE Na3AlF6
aluminium and oxide ions are now free to moveSAVES ENERGY - the mixture melts at a lower temperature
Electrons will flow from most reactive to least
reactive electrode
finish
Evaluate the importance of conditions needed for extraction of aluminium
BAUXITE aluminium ore
Bauxite contains alumina (Al2O3 aluminium oxide) plus impurities such as iron oxide – it is purified before use.
CRYOLITE Aluminium oxide Al2O3 has a veryhigh melting point.Adding cryolite Na3 AlF6 lowers the
melting point and saves energy.
THE CARBON ANODES REACT
WITH THE OXYGEN TO PRODUCE
CARBON DIOXIDE
THE CARBON ANODES HAVE TO BE REPLACED AT REGULAR INTERVALS, THUS ADDING TO THE
COST OF THE EXTRACTION PROCESS
USES OF ALUMINIUM
THE IMPORTANCE OF ALUMINIUM
LOW DENSITY AND OVERHEAD CABLESELECTRICAL CONDUCTIVITY
LOW DENSITY AIRCRAFT BODIESneeds to be an alloyed withother metals for extra strength
GOOD HEAT CONDUCTIVITY SAUCEPANS
USES OF ALUMINIUM
THE IMPORTANCE OF ALUMINIUM
LOW DENSITY AND OVERHEAD CABLESELECTRICAL CONDUCTIVITY
LOW DENSITY AIRCRAFT BODIESneeds to be an alloyed withother metals for extra strength
GOOD HEAT CONDUCTIVITY SAUCEPANS
Syllabus wants you to quote theses uses and reasons
Here are the answers, what are the questions?....
• Think of the questions related to the answers found on the worksheet provided
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