What is the coordination entity formed when excess of aqueous \(KCN\) is added to an aqueous solution of copper sulphate? Why is it that no precipitate of copper sulphide is obtained when \(H_2S(g)\) is passed through this solution?
What is the coordination entity formed when excess of aqueous \(KCN\) is added to an aqueous solution of copper sulphate? Why is it that no precipitate of copper sulphide is obtained when \(H_2S(g)\) is passed through this solution?
Solution and Explanation
\(CuSO_{4(aq)}+4KCN_{(aq)}→K_2[Cu(CN)_4]_{(aq)}+K_2SO_4\)
i.e,\([Cu(H_2O)_4]^{2+}+4CN^{-}→[Cu(CN)_4]^{2-}+4H_2O\)
Thus, the coordination entity formed in the process is \(K_2[Cu(CN)_4]\). \(K_2[Cu(CN)_4]\) is a very stable complex, which does not ionize to give \(Cu^{2+}\) ions when added to water. Hence, \(Cu^{2+}\) ions are not precipitated when \(H_2S_{(g)}\)is passed through the solution.
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Concepts Used:
Applications of Coordination Compounds
There are three applications of coordination compounds:
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- Copper-complex enzymes important to iron storage and producing pigments in hair, skin, and eyes.
- Nickel-complex enzymes as part of the enzymes urease and hydrogenase