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Homework Help: Percent Ionization Ka

  1. Feb 25, 2010 #1
    1. The problem statement, all variables and given/known data
    What concentration of formic acid would give an aqueous solution in which 2.85 percent of the formic acid molecules are ionized? Assume that Ka for formic acid is 1.80E-4 .

    2. Relevant equations

    3. The attempt at a solution

    X^2 / .0285 - X = 1.8E-4
    X = .00226
    M = .0285 - .00226 = .0262M
    This is wrong. Any ideas?
  2. jcsd
  3. Feb 25, 2010 #2


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    Let X be the concentration of formic acid before dissociation. 0.0285X represents what?

    Can you get there from here?
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