Solubility Issues
A ligand increases the solubility of a slightly soluble ionic compound
if it forms a complex ion with the cation.
ZnS(s) + H2O(l) Zn2+(aq) + HS-(aq) + OH-(aq) Ksp = 2.0 x 10-22
Upon addition of some 1.0 M NaCN:
Zn2+(aq) + 4CN-(aq) Zn(CN)42+(aq) Kf = 4.2 x 1019
The overall equation is:
ZnS(s) + 4CN-(aq) + H2O(l) Zn(CN)42+(aq) + HS-(aq) + OH-(aq)
Koverall = Ksp x Kf = 8.4 x 10-3
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