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What is the pH of this new solution?

  1. Jul 1, 2016 #1


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    1. The problem statement, all variables and given/known data

    Equal volumes of two solutions of hydrochloric acid are mixed. One solution has a pH 1 while the other pH 5. The pH of the solution obtained is?

    A) Less than 1

    B) Between 1 and 2

    C) 3

    D) Between 4 and 5

    E) More than 5

    2. Relevant equations
    -log[H+] = pH
    10-pH = [H+]

    3. The attempt at a solution
    let v = volume of solution 1 added

    number of mol of H+ in solution with pH 1:
    10-1 * v

    number of mol of H+ in solution with pH 5:
    10-5 * v

    molarity of H+ in new solution
    $$\frac {10^{-1} * v + 10^{-5} *v} {2v}$$

    therefore $$pH = -log(\frac {10^{-1} + 10^{-5}}{2})$$

    Hence pH = 1.300

    Answer is B.

    Is this correct?
  2. jcsd
  3. Jul 2, 2016 #2
    Yes, nicely done.
  4. Jul 2, 2016 #3


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    Sweet, cheers!
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