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    0.500g of bronze was reacted with nitric acid giving a Cu2+*solution.* The solution was reacted with iodide ions, I-*forming a solution of iodine, I2.

    This iodine solution*was then titrated with 0.200 mol dm-3*solution of sodium thiosulphate, 22.40cm3*of this was required.

    Calculate the % by mass of copper in bronze

    I did 0.2*(22.40/1000) = 0.00448 which were the moles of thiosulphate which I then divide by 2 to get moles of I2.

    Now that I have moles of I2 - this gives me the moles of Cu2+ which I multiple the mols of I2 by 2 to get. then I do 63.5*mol of Cu2+ to give me mass of copper. Then mass of copper/0.5 * 100 to get percentage composition? Is this method correct?

    (Original post by MrToodles4)
    Is this method correct?
    Your route through the problem is correct, it is just your molar ratios are a bit squiffy.

    Can you show us your balanced overall reactions between Cu2+ and I- and between I- and S2O32-?
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