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.
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!
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this doesn't make sense
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