Chemistry solubility (Ksp)

  • Thread starter NOP90
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  • #1
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Homework Statement


What is the solubility (M) of PbCl2 in a0.15M solution of HCl? The Ksp of PbCl2 is 1.6*10^-5

answer is 7.4*10^-4


Homework Equations


Ksp= [Pb] * [Cl]^2


The Attempt at a Solution


Like the other question I posted I need help with the working. I tried 4x^3 = 1.6*10^-5 which led to wrong answer and also 1.6*10^-5 / different forms of 0.15 [(0.15), (0.15*2), (0.15^2), (2*0.15^2)]
 

Answers and Replies

  • #2
Borek
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Take a look at Ksp formula. Solution already contains Cl- anions, so you can't ignore them, you must take them into account. 4x^3 = 1.6*10^-5 would work only when there are no other sources of neither lead or chloride. If I understand correctly your other trials - while blind - tried to take this into account, but you ignored something else - when lead chloride dissolves, concentration of chlorides goes up.

Don't hunt for 7.4e-4, as it is not the correct answer.
 

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