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Determine the amount of NaOH and Sr(OH)2 based on pOH

  1. Jun 26, 2016 #1
    1. The problem statement, all variables and given/known data
    I am trying to solve the following problem:
    A 4.00-L base solution contains 0.100 mol total of

    NaOH and Sr(OH)2 . The pOH of the solution is 1.51.

    Determine the amounts (in moles) of NaOH and

    Sr(OH)2 in the solution.

    2. Relevant equations
    3. The attempt at a solution

    I am stuck because I am not sure I correctly constructing the solution path:

    We have pOH = 1.51, which means that there are 10^(-1.51) moles of OH in solution, i.e. 0.0309 moles per one liter of solution. If I have 4 liters, then shouldn't there be 0.1236 moles of OH in this solution?
    But according to the problem there are only 0.100 moles of NaOH and Sr(OH)2; both are strong bases, therefore there 0.100 moles of OH in the 4 liters of solution. How can that be?
    Where is my mistake?
    Thank you very much!
  2. jcsd
  3. Jun 26, 2016 #2


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    Staff: Mentor

    How many moles of OH- are produced per 1 mole of dissociating Sr(OH)2?
  4. Jun 27, 2016 #3
    2 moles. There are 3 moles of OH- produced by dissociating both NaOH and Sr(OH)2, and two of those come from dissociating Sr(OH)2
  5. Jun 27, 2016 #4


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    Staff: Mentor

    What does it mean

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