FeSO4 solution mixed with (NH4)2SO4 solution in 1:1 molar ratio gives the test of Fe2+ ion but CuSO4 solution mixed with aqueous ammonia in 1:4 molar ratio does not give the test of Cu2+ ion. Explain why.
Case 1: FeSO4 mixed with (NH4)2SO4 On mixing both, FeSO4 does not form complexes but forms a double salt, FeSO4.(NH4)2SO4.6H2O which dissociates completely into ions. This double salt is commonly called Mohr's salt. The reaction equation is shown below: FeSO4 + 6H2O + (NH4)2SO4→ FeSO4.(NH4)2SO4.6H2O Case 2: CuSO4 mixed with (NH4)2SO4 Copper sulphate when mixed forms complex [Cu(NH3)4]SO4 in which Cu ions do not completely dissociate. The complex on dissociation forms Cu[(NH3)4]2+. CuSO4+4NH3+5H<
