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Homework Help: Calculating pH given M

  1. Oct 15, 2008 #1
    1. The problem statement, all variables and given/known data

    The pH of a 1.00x10-8 M solution of HClO4 is

    2. Relevant equations


    3. The attempt at a solution

    I thought I could just do -log(1.00x10^8) = 8, but the answer is actually 6.98. Why?

    Does it have anything to do with it being a strong acid?
  2. jcsd
  3. Oct 15, 2008 #2
    Since the concentration is extremely dilute and is < 1e-7, a phenomenon known as autoionization of water takes place...check out Example 3 under Strong Acids on http://www.science.uwaterloo.ca/~cchieh/cact/c123/stacids.html" [Broken]for how to solve.
    Last edited by a moderator: May 3, 2017
  4. Oct 15, 2008 #3
    thanks a lot.
    Last edited by a moderator: May 3, 2017
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