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    pls help. i got a percentage of 77.7 percent and i looked at the mark scheme and i just dont understand how theyve multiplied the moles of the ferrate ion by 2/3???
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    the question is:

    the solid sample of barium ferrate (6) obtained in step 2 is impure. .
    determine the percentage, by mass of barium ferrate in the 0.437 g of solid fformed in step 2
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    Calculate moles of S2O3 and apply moles of I2 using the 2:1 ratio
    You have to remember that step 4 is a follow-on reaction from step 3, this means that whatever moles you have of iodine you have in step 4 you will have the same amount in step 3. So don't get confused by the 1:1.5 ratio between 4 and 3.
    You have X many moles of I2, which is in a 1.5:1 ratio with your iron Barium Ferrate. So we apply the ratio to calculate moles of ferrate. Now times by the Mr of ferrate (Mr is around 257) and then you should know how to calculate your impurity by expected mass divided by actual mass of barium ferrate
 
 
 
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