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    Hello, just a past paper question I was looking it says

    About five thousand years passed between the first extraction of iron and that of aluminium. Explain why?


    Emmm do i need to know a bit of history here? lol

    Thanks

    From John Wood
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    (Original post by Neo1)
    Hello, just a past paper question I was looking it says

    About five thousand years passed between the first extraction of iron and that of aluminium. Explain why?


    Emmm do i need to know a bit of history here? lol

    Thanks

    From John Wood
    Because you have have to use electrolysis to extract aluminium from it's ore bauxite Al203. Molten aluminium is dissolved in cyolite at a temperature of 2000 degrees then electrolysis can occur

    Cathode:
    Al3+ + 3e- --> Al

    Anode:
    2O2- --> O2 + 2e-


    Whereas iron can be extracted from it's ore haematite by reduction with carbon and heat.

    2Fe2CO3 + 3C --> 2Fe + 3CO2

    Therefore aluminium took longer to extract because electricity needed to be invented and a way of dissolving Al2O3 before the extraction can occur. Whereas with iron you can simply use C as a reducing agent (note you can't reduce aluminium with carbon because Al is more reactive than carbon... i think that's the reason anyway)

    In industry though, which is what i had to know, CO is used as the reducing agent.

    Coke burns in oxygen:

    C + O2 --> CO2

    CO2 + C --> 2CO

    Fe2CO3 + CO --> 2Fe + 2CO2


    The SO2 reacts with CaCO3 forming **** when removed.
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    (Original post by Revenged)
    Because you have have to use electrolysis to extract aluminium from it's ore bauxite Al203. Molten aluminium is dissolved in cyolite at a temperature of 2000 degrees then electrolysis can occur

    Cathode:
    Al3+ + 3e- --> Al

    Anode:
    2O2- --> O2 + 2e-


    Whereas iron can be extracted from it's ore haematite by reduction with carbon and heat.

    2Fe2CO3 + 3C --> 2Fe + 3CO2

    Therefore aluminium took longer to extract because electricity needed to be invented and a way of dissolving Al2O3 before the extraction can occur. Whereas with iron you can simply use C as a reducing agent (note you can't reduce aluminium with carbon because Al is more reactive than carbon... i think that's the reason anyway)

    In industry though, which is what i had to know, CO is used as the reducing agent.

    Coke burns in oxygen:

    C + O2 --> CO2

    CO2 + C --> 2CO

    Fe2CO3 + CO --> 2Fe + 2CO2


    The SO2 reacts with CaCO3 forming **** when removed.
    just a couple of typos:-

    the limestone (CaCO3) decomposes in the hot furnace to CaO which then reacts with the silicon dioxide impurity in the iron ore to give calcium silicate (****) which floats on the molten iron and is tapped off.

    The equation should read Fe2O3 without the carbon atom!
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    How many marks for this question mate?
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    (Original post by charco)
    the limestone (CaCO3) decomposes in the hot furnace to CaO which then reacts with the silicon dioxide impurity in the iron ore to give calcium silicate (****) which floats on the molten iron and is tapped off.
    Cheers, i forgot that actually!
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    Great explanation Revenged! (pity about the typos )
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    i know, colour coded and everythin... i wish i was paid to do this, lol!
 
 
 
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