Aqueous copper sulphate solution (blue in colour) gives:

(i) a green precipitate with aqueous potassium fluoride and


(ii) a bright green solution with aqueous potassium chloride. Explain these experimental results.

Copper sulphate exists as [Cu(H2O)4]SO4 . It is blue in colour due to presence of the [Cu(H2O)4]2+ ions.


When KF is added water is replaced by fluoride ion and green colour is due to [Cu(F)4]2- ions.


When KCl is added water is replaced by chloride ion and bright green colour is due to presence of [CuCl4]2- ions.


In both the cases water , weak field ligand is replaced by fluoride and chloride ions.


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