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Homework Help: 1997 Ap Chem Free Response #9 Help

  1. Nov 4, 2007 #1
    Hey, I have a worksheet due tomorrow for my chem class and it includes #9 from the 1997 FR AP Chem Test. I can't figure it out! Any help would be appreciated!
    Here goes:
    An experiment is to be performed to determine the mass percent of sulfate in an unknown soluble sulfate salt. The equiptment available is: a scale, a funnel, a grad cylinder, a ringstand, a beaker, a stirring rod .20 M BaCl2, Unknown sulfate salt, and a drying oven.
    a) Explain a procedure to carry this out.
    b) What experimental data needs to be collected to calculate the mass percent of sulfate in the unknown
    c) List the calculations necessary to determine the mass percent of sulfate in the unknown
    d) Would .2 M MgCl2 be an acceptable subsitsute for the BaCl2 solution provided for this experiment? Explain.

  2. jcsd
  3. Nov 4, 2007 #2
    even if you can't figure it all out, give it a try and tell us what you think is needed here and we'll help you along
  4. Nov 4, 2007 #3
    dude, do you think i didn't TRY to do the problem? thats why i'm asking the question... because i cant do it. If i could then I wouldnt need your help....
    Last edited: Nov 4, 2007
  5. Nov 4, 2007 #4
    calm down, just make a guess atleast what you should do. then we can look at your work and make corrections. So, show us an attempt, doesn't have to be a correct one. I know you really want a solution, but I promise you, you will remember this problem better and have a better understanding of the nature of its inner workings if you attempt to work it out whether or not it is correct and have us look at it and give you hints and suggestions or corrections.
    Last edited: Nov 4, 2007
  6. Nov 4, 2007 #5


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    You need to know that SO4(-2) + BaCl2 ==> BaSO4 + 2Cl(-2)
    and that Barium Sulfate is insoluble, therefore is a precipitate.

    I'm not sure about the solubility of MgSO4. Check a handbook or solubility rules in your textbook.
  7. Nov 5, 2007 #6
    Thanks man!
  8. Nov 5, 2007 #7
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