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Homework Help: Chemical equilibrium problem pls help reply soon plss

  1. Jul 24, 2008 #1
    1. The problem statement, all variables and given/known data
    A sol'n contains Cu+2(aq) and Zn+2 ions each at a con'c of 0.1M. Hydrogen sulphide gas is bubbled up into sol'n and dissociates having an initial con'c of 0.1M. Whats the pH of the final solution? Will any precipate form?
    I dont know how to start the problem. Pls help me and reply soon.

    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jul 24, 2008 #2

    Borek

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    Staff: Mentor

    H2S is a weak diprotic acid. Differences between both dissociation constants are large enough to calculate each dissociation equilibrium separately. You have to check what the pH is (it i will be solely governed by the first dissociation step), use this pH value to calculate S2- concentration, and check if this concetration will be large enough for precipitation (hint: look for Kso values).

    For more details see this page on the pH of polyprotic substance calculation.
     
  4. Jul 24, 2008 #3
    thanks for your reply Borek,

    can u tell equation of this equilibrium problem so that i can solve it further. THat would be really helpful.
    Once again, thanks for your reply.
     
  5. Jul 24, 2008 #4

    Borek

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    Staff: Mentor

    All equations that you need to calculate pH of the solution and S2-[/sup concentration are listed on my site.
     
  6. Jul 31, 2008 #5

    chemisttree

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    Are you still having problems with this question?
     
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