What is the Difference Between Complex Salt and Double Salt?

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The main differences between complex salt and double salt are:

  1. Formation: Double salts are formed through the combination of two different salts with similar crystalline structures, while complex salts are formed when a coordination complex, which consists of a central metal ion surrounded by ligands, combines with one or more simple ions.
  2. Dissociation in water: Double salts can give simple ions when added to water, as they dissociate into their constituent ions. Complex salts, on the other hand, do not give simple ions when added to water. Instead, they dissociate with at least one complex ion.
  3. Properties: The properties of double salts are similar to those of their constituent salts. Complex salts, however, exhibit unique chemical and physical properties, such as high stability and catalytic activity, which are different from their constituent elements.
  4. Structure: Double salts possess a specific stoichiometric ratio, where the constituent ions combine in fixed proportions within the crystal lattice. This results in a compound with distinct physical and chemical properties, including altered solubilities, unique colors, and different crystalline structures. Complex salts have intricate structures and often exhibit unique chemical and physical properties.
  5. Identity in solution: Double salts lose their identity when dissolved in water, and their properties are consistent with those of their individual salt components. Complex salts retain their identity in solution and exhibit properties that are distinct from their individual components.

Comparative Table: Complex Salt vs Double Salt

Complex salts and double salts are both types of chemical compounds that contain more than one type of cation or anion. However, they differ in their formation, dissociation, and properties. Here is a table comparing the differences between complex salts and double salts:

Complex Salts Double Salts
Formed by the reaction of a coordination compound with an anion or another coordination compound Formed by the reaction of two simple salts in a specific stoichiometric ratio
Exist in both the solid state and aqueous or non-aqueous solutions Exist only in the solid state and dissociate into their constituent ions in the solution
Do not lose their identity completely in the solution Lose their identity in the solution
Properties are different from their constituents Properties are the same as those of their constituents
Metal ions show two valences: primary and secondary Metal ions show their normal valence
Coordination complex dissociates in water with at least one complex ion Dissociates in water completely into simple ions

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