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chemistry

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Ignoring activities, determine the molar solubility (S) of Zn(CN)2 in a solution with a pH = 3.63. Ksp (Zn(CN)2) = 3.0 × 10-16; Ka (HCN) = 6.2 × 10-10.

I'm completely lost help please!

  • chemistry - ,

    You can work this one of two ways. Here is one way; I don't know which would be easier for you to understand.
    Zn(CN)2 ==> Zn + 2CN^-
    Then 2CN^- + 2H^+ ==> 2HCN.
    Solubility Zn(CN)2 = S
    Then Zn^2+ = S and
    CN^- = 2S. The total CN = 2S and
    2S = (CN^-) + (HCN)

    Use Ka for HCN = (H^+)(CN^-)/(HCN)
    Solve for (HCN)/(CN^-) = and convert that to (HCN) = (CN^-)*some number.
    Then go back to 2S = CN + HCN
    and this becomes 2S = CN + somenumber*CN
    and convert this to CN = ? in terms of S.
    Plug this back into Ksp and solve for S. I get a value of 0.022 M. Try this and see if you understand. If so there is no need to go through the other method.

  • chemistry - ,

    this doesn't make sense

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