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What is BaCl2 * 5H2O

  1. Jul 31, 2003 #1
    Chemistry help plz!!

    I've tried to work out the problem below, but I got weird answer, it's not even in one of the choices. Please help me solve this problem and show me out u got it. Thank you.
    A sample of a hydrate of BaCl2 with a mass of 61 grams was heated until all the water was removed. The sample was then weighed and found to have a mass of 52 grams. What is the formula for the hydrate?
    (A) BaCl2 * 5H2O
    (B) BaCl2 * 4H2O
    (C) BaCl2 * 3H2O
    (D) BaCl2 * 2H2O
    (E) BaCl2 * H2O
  2. jcsd
  3. Aug 1, 2003 #2

    Ivan Seeking

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    Re: Chemistry help plz!!

    Starting with your equation: BaCl2 + MH2O

    Then, N x grams per mole of (BaCl2 + MH2O) = 61 grams

    N is the number of moles of the hydrate.

    Where we must determine the coefficient M.

    You know that you have removed 9 grams of water:

    M x (N moles of H2O at [(2 X 1.008) + 15.99]grams/mol) = 9 grams

    Solve for N,
    N moles of BaCl2 at [137.34 + (2 X 35.45)] = 52 grams.

    then M.
    Last edited: Aug 1, 2003
  4. Aug 1, 2003 #3
    In a problem like this you figure out how many moles of **** you got.

    You've got 52 of straight up BaCl2. That's 208 grams per mole, so 52/208 = 0.25 moles.

    You've got 9 grams of water at 18 grams/mole, so you've got 0.5 moles H20.

    So then if you can't figure out the rest you deserve that bad grade. (-;
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