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Dimensional Analysis and pH

  1. Jul 31, 2012 #1


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    This is something I've been wondering for a while, but I thought that the inputs for things like ln(x), e(x), sin(x), etc. had to be unitless. Then how come concentration, which has units of moles per volume (or I guess just per volume, since moles are just a number? I've never been sure about that...) is used as an input for log(x) to find pH, pOH, pKa, etc.?
  2. jcsd
  3. Jul 31, 2012 #2
    I've never thought about that myself.

    I would suspect it is because formula pH is defined as, pH=-log(a) where a is the activity of the hydrogen ion and activity is dimensionless.
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