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Homework Help: Percent Composition and Finding Formula - Chemistry

  1. Mar 12, 2008 #1
    % Composition and Finding Formula - Chemistry

    50.0g of Sulphur is mixed with 100.0g of iron and heated strongly. When the reaction is complete 12.5g of iron remains. What is the formula of the sulphide formed?

    What i have done so far is i got the 2 mols of each element.


    i divided biggest/smallest and i get 1.41
    now i need to know how to put it in ratio form and what to do to find the formula for Sulphide
  2. jcsd
  3. Mar 12, 2008 #2
    it said 12.5g of Fe was unreacted!!
  4. Mar 12, 2008 #3
    hmm so i should go 100-12.5 then find the mol then find the ratio?
  5. Mar 12, 2008 #4
    yeah..... this is it....

    you divide the mass reacted by the respective atomic mass. then you find the ratio.
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