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    For this I did:

    159.6g of Iron oxide ---> 111.6g of iron, so as 700 tonnes of iron produced, (700/111.6) x 159.6 = 1001.1 tonnes, is this correct? As the mark scheme says 1000 but I'm not sure if that's due to rounding.

    For the second part

    159.6g of iron oxide requires 84g of CO to fully react, so scaling this up to the 1000 of iron oxide would require 526.3g of carbon monoxide

    so using the second reaction, 24g of coke produces 56g of carbon monoxide, so we would need (526.3/56) x 24 = 255.5g of coke? But the mark scheme says 527, so I'm pretty sure I've gone wrong somewhere in this whole question. Any help would be appreciated, thanks!

    This is what I've done:

    PART A

    700 tonnes of Fe = 7x108 g of Fe

    2 moles of Fe is produced from 1 mole of Fe2O3
    RMM of Fe = 55.8g mol-1
    RMM of Fe2O3 = 159.6g mol-1

    Moles of Fe = Mass/RMM
    = 7x108g / 55.8g mol-1
    = 1.25x107 mol

    There is a 2:1 ratio between Fe and Fe2O3, therefore
    1.25x107 mol of Fe = 6.25x106 mol of Fe2O3

    Mass of Fe2O3 = Moles x RMM
    = 6.25x106 mol x 159.6g mol-1
    = 9.975x108g
    = 9.975x105kg
    = 9.975x102 tonnes
    = 991.5 tonnes (or 1000 tonnes rounded up)

    PART B

    1 mol of Fe2O3 requires 3/2 moles of CO from the second reaction
    Moles of CO = 1.25x107 x (3/2)
    =1.875x107 mol

    There is a 1:1 ratio between CO and C and so
    1.875x107 mol CO = 1.875x107 mol of C

    Mass of C = Moles x RMM
    = 1.875x107 mol x 12g mol-1
    = 2.25x108g
    = 2.25x105kg
    = 225 tonnes

    I see no possible way that it could be 527 tonnes...
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