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Acids, bases and pH

  1. Dec 12, 2006 #1
    1. The problem statement, all variables and given/known data
    find the pH of:
    100mL x .20M HOAc + 100mL x.10M Ba(OH)2

    3. The attempt at a solution

    100x.2 = 20mmol HOAc
    100x.1 = 10mmol Ba(OH)2
    pOH = -log(.05) = 1.3

    Is this correct?
  2. jcsd
  3. Dec 13, 2006 #2


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    Staff: Mentor

    No. Ba(OH)2 is 'diprotic'.
  4. Dec 15, 2006 #3


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    Ba(OH)2 is not diprotic. Dibasic.

    Think in terms of equivalents instead of moles (or mmol) with the barium hydroxide...

    BTW, the way you did the work, it wasn't clear (to you) whether the "10" left over in the reaction was barium or acetic acid. Using the logic you provided, the acetic acid was actually present in excess and the pH should have been less than 7.

    Using equivalents in place of moles should "completely neutralize" any misunderstanding you may have.
  5. Dec 15, 2006 #4


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    hint, hint, the situation is going to be "neutralized" as chemisttree has said

    However, the conjugate of the acetic acid is a base with a significant Kb, you're going to need to use the Kb equation to find the [OH-], then the pH through further calculations.
  6. Dec 18, 2006 #5


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    Staff: Mentor

    That's what happens when English is not your first language... :grumpy:

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