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

  • Thread starter ducmod
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Homework Statement


Hello!
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.

Homework Equations


3. The Attempt at a Solution [/B]
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!
 

Answers and Replies

  • #2
Borek
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28,628
3,102
How many moles of OH- are produced per 1 mole of dissociating Sr(OH)2?
 
  • #3
86
0
How many moles of OH- are produced per 1 mole of dissociating Sr(OH)2?
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
 
  • #4
Borek
Mentor
28,628
3,102
What does it mean

solution contains 0.100 mol total of NaOH and Sr(OH)2
 

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