Question

Answer in brief.

What is the difference between a double salt and a complex? Give an example.

Answer 1

Double salt	Complex
(1) Double salts exist only in the solid state and dissociate into their constituent ions in the aqueous solutions.	(1) Coordination compounds exist in the solid-state as well as in the aqueous or non-aqueous solutions.
(2) Double salts lose their identity in the solution.	(2) They do not lose their identity completely.
(3) The properties of double salts are same as those of their constituents.	(3) The properties of coordination compounds are different from their constituents.
(4) Metal ions in the double salts show their normal valence.	(4) Metal ions in the coordination compounds show two valences namely primary valence and second­ary valence satisfied by anions or neutral molecules called ligands.
(5) For example in K2SO4. K2SO4. A12(SO4)3. 24H2O. The ions K+, Al3 + and SO4 show their properties.	(5) In K4[Fe(CN)6], ions K+ and [Fe(CN)6]4‘~ ions show their properties.

Answer 2

A double salt dissociates in water completely into simple ions, whereas a coordination complex dissociates in water with at least one complex ion.

e.g. Mohr's salt, FeSO₄(NH₄)₂SO₄.6H₂O is a double salt while K₄[Fe(CN)₆] is a complex.