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


CARBON ANODE

THE CELL CONSISTS OF A CARBON ANODE

Help 2


STEEL CATHODECARBON LINING

THE CELL CONSISTS OF A CARBON LINED STEEL CATHODE (iron and carbon)

Help 3


MOLTEN ALUMINA and

CRYOLITE

ALUMINA IS DISSOLVED IN MOLTEN CRYOLITE Na3AlF6

SAVES ENERGY - the mixture melts at a lower temperature

Help 4


MOLTEN ALUMINA and

CRYOLITE


aluminium and oxide ions are now free to move

Help 5


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-


NEGATIVE OXIDE IONS ARE

ATTRACTED TO THE POSITIVE

ANODE

EACH ION GIVES UP 2 ELECTRONS AND IS DISCHARGED

CARBON ANODE

Help 7


ELECTRONS

CARBON ANODE

CARBON CATHODE

Electrons will flow from most reactive to least

reactive electrode

Help 8


ELECTRONS

ANODE OXIDATION

OXIDATION (LOSS OF ELECTRONS) TAKES PLACE

AT THE ANODECARBON ANODE

Help 9


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


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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making aluminium

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