a. Double salts are the molecular or addition compounds that exist only in solid state and dissociate into ions in aqueous solution or in any other solvent. They lose their identity in aqueous solution. Fe(NH4)2(SO4)2(H2O)6 or Mohr’s salt is a double salt, which dissolves in water and gives the characteristics of Fe2+, \(NH^+_4\) and \(SO^{2-}_4\) ions.
b. Coordination compounds are the molecular or addition compounds that exist in the solid state as well as when dissolved in water or any other solvent. They do not completely lose their identity in aqueous solution. K4[Fe(CN)6] is a coordination compound and when dissolved in water its constituent complex ion [Fe(CN)6]4- does not dissociate into Fe2+ and CN- ions.
