[danny411]

electrolysis of molten al203

write the anode and cath and min required voltage

since its not at stp then i can use my chart ?

but i think the equations are

cathode al3+ +3e----> al(s)   ===-1.66 since there are 2 al then -3.32 v

anode i dont know but i figure : c(s) +20(2-) ----> co2  + 4e-

i added them all together to get co---->c02 +4e   ==== 0.28 ?

charge neeed : -3.04 ?

ok im totally lost on that one ?

basically c(s) is on the cath and anode to start the process...al203 is dumped into crylic to dissociate it?

[cliverlong]

The following is a clear description of the electrolysis of molten bauxite

http://www.bbc.co.uk/schools/gcsebitesize/chemistry/usefulproductsrocks/electrolysisrev3.shtml

electrolysis of molten al203

cathode al3+ +3e----> al(s)   ===-1.66 since there are 2 al then -3.32 v

No.

The voltage just depends on the electrode potential of Al³⁺ | Al. The fact that the balanced equation

Al₂O₃ > 2Al + 1.5 O₂

liberates 2 moles of Aluminium from one mole of "pure" ore just affects the amount of charge (or current) required, not the voltage.

anode i dont know but i figure : c(s) +20(2-) ----> co2  + 4e-

i added them all together to get co---->c02 +4e   ==== 0.28 ?

charge neeed : -3.04 ?

ok im totally lost on that one ?

I think you just need to concentrate on the half cells

Al³⁺ | Al
O^2- | 1/2 O2

and ignore the reaction of oxygen with carbon anode.

basically c(s) is on the cath and anode to start the process...al203 is dumped into crylic to dissociate it?

I don't think that is right

From the reference I gave at the start

• Cryolite reduces the boiling point of bauxite thereby reducing the energy required for the overall electrolysis process
• Graphite anodes are used (maybe) because they 1) conduct electricity 2) can withstand the molten temperatures, 3) do not react with the aluminium 4) react with the oxygen to form "less flammable" carbon dioxide

Clive