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Homework Help: Determing Molarity. Did I do it right?

  1. Feb 26, 2010 #1
    The questions asks us to: Determine the molar concentration of I- in a reaction mixture. The reaction was as follows (data):

    20 mL of .1 M KI
    0 mL of .1 M KCl
    10 mL of .003 M Thiosulfate
    20 mL of .10 M Persulfate

    I did the following:

    20 ml I- x (1 L / 1000 mL) = .02 L I-

    .02 L I- x (.1 mol / 1 L) = .002 mol I-

    .002 mol / .05 L solution (20 mL + 0 mL + 10 mL + 20 mL) = .04 M I-

    Little rusty, wanted to make sure I did this right.

    Any help will be greatly appreciated!
    Last edited: Feb 26, 2010
  2. jcsd
  3. Feb 26, 2010 #2


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    Staff: Mentor

    Question is ambiguous. Does it ask for initial concentration, or for concentration after reaction took place?

    Initial looks OK to me.

  4. Feb 26, 2010 #3
    k, going with it heh. I do believe it is initial because we have no post-reaction data.
  5. Feb 26, 2010 #4


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    Staff: Mentor

    Well, you may calculate post reaction from stoichiometry.

    I have not checked, but could be final concentration of I- is identical to initial.

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