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    Hello
    It's from Paper 1 Edexcel, in the Multiple choice section:


    17.1 g of aluminium sulfate, Al2(SO4)3, was dissolved in water.
    Calculate the number of sulfate ions, SO4(2–), present in the solution formed.
    [Assume the molar mass of Al2(SO4)3 is 342 g mol–1 and the Avogadro Constant is
    6 × 10^23 mol–1.]

    A 3 × 10^21

    B 1 × 10^22

    C 3 × 10^22

    D 9 × 10^22

    Now I did (17.1/342) x 6x10^23 which gave C, but that isn't the right answer when I checked in the mark scheme, it's actually D.
    Could someone just show me the extra step to get to that answer? Thanks
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    17.1/342 is the amount of Al2(SO4)3 in mol. However, each Al2(SO4)3 particle produces 3 (SO4)2- ions on dissolving. Hence the correct answer is your answer multiplied by 3.
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    Ah right! I thought I was on the right lines but I didn't see what to do next. I absolutely loathe multiple choice haha, cheers!
 
 
 
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