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Homework Help: Stociometry problem

  1. Aug 30, 2007 #1
    1. The problem statement, all variables and given/known data

    What is the atomic mass of element X if 6.08 g XCl3 contains 1.37 g of X

    2. Relevant equations

    3. The attempt at a solution

    (6.08 g XCl^3)*(1 mol X/107.729 g *XCl3)*(1.37 g X/1 mol X)=.077 g of X

    That can't be right , because 1.37 g of X can't be included in the molar mass of XCl3
  2. jcsd
  3. Aug 30, 2007 #2


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    Long time since passed since doing stoichiometry exercises...

    Total XCl3 was 6.08, since grams X was 1.37, amount of Cl mass was 4.71 grams.

    How many formula units Cl ? 4.71/(35.5);
    Ratio of X formula units to Cl formula units = 1/3

    How many moles of X ? ((4.71)/(35.5))*(1/3)

    Now you have calculated moles of X or formula units of X, and were given grams of X.
    Finish the calculation.
  4. Aug 31, 2007 #3


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    Roco, your answer was correct, but we can't go about handing out complete solutions to homework questions.

    Benzoate, to simplify symbolipt's method a wee bit...

    Answer this question: If there's 4.71 gms of Cl3 and 1.37 gms of X (in a sample of XCl3), what is the formula mass of X?
  5. Aug 31, 2007 #4
    sorry! will comply.
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