Complex Salt vs. Double Salt

What's the Difference?

Complex salt and double salt are both types of salts that contain more than one type of cation or anion. However, they differ in their composition and structure. Complex salt is formed when a metal cation is coordinated with a complex ion, such as a ligand. This coordination results in a stable complex with a specific chemical formula. On the other hand, double salt is formed when two different salts are combined in a specific ratio, resulting in a new compound with its own unique chemical formula. In double salts, the individual ions of each salt remain separate and do not form complex ions. Overall, complex salts have a more intricate structure due to the coordination of metal cations with ligands, while double salts are a combination of two separate salts.


AttributeComplex SaltDouble Salt
SolubilityMay have lower solubility in waterGenerally more soluble in water
CompositionContains a complex ionContains two different ions
FormationFormed by the reaction of a complex ion with a simple ionFormed by the reaction of two different simple ions
StructureUsually have a more complex crystal structureUsually have a simpler crystal structure
ExamplesPotassium hexacyanoferrate(II)Potassium alum

Further Detail


Salt is a fundamental component in our daily lives, used for various purposes ranging from cooking to industrial applications. Within the realm of salts, there are different types, including complex salt and double salt. While both types share similarities, they also possess distinct attributes that set them apart. In this article, we will explore and compare the attributes of complex salt and double salt, shedding light on their composition, formation, properties, and applications.


Complex salt, also known as coordination compound, is formed by the combination of a metal ion and a complex ion. The metal ion acts as the central atom, surrounded by ligands that coordinate with it through coordinate covalent bonds. These ligands can be neutral molecules or anions. The resulting complex salt has a well-defined chemical formula, indicating the exact ratio of metal ion to ligands.

On the other hand, double salt is formed by the combination of two different salts. Unlike complex salt, double salt does not involve coordination compounds. Instead, it consists of two distinct ionic compounds that are chemically bonded together. The two salts retain their individual chemical formulas and crystal structures within the double salt.


Complex salts are typically formed through the reaction between a metal ion and a ligand. The ligand donates a pair of electrons to the metal ion, forming a coordinate covalent bond. This process can occur in solution or through solid-state reactions. The formation of complex salts often requires specific conditions, such as the presence of suitable ligands and appropriate pH levels.

Double salts, on the other hand, are formed through the combination of two different salts. This can occur when two salt solutions are mixed together, and a chemical reaction takes place, resulting in the formation of a new compound. The formation of double salts is influenced by factors such as temperature, concentration, and the solubility of the individual salts.


Complex salts exhibit unique properties due to the presence of coordination compounds. They often have complex crystal structures, with the metal ion at the center surrounded by ligands in specific geometries. These compounds can display a wide range of colors, from vibrant hues to colorless forms. Complex salts also tend to have higher melting and boiling points compared to double salts.

Double salts, on the other hand, retain the properties of their individual salts. They possess well-defined crystal structures, with the two salts arranged in a specific pattern. Double salts can exhibit different colors depending on the combination of salts involved. They generally have lower melting and boiling points compared to complex salts.


Complex salts find applications in various fields, including medicine, catalysis, and materials science. In medicine, complex salts are used as therapeutic agents, where the metal ion plays a crucial role in the desired biological activity. In catalysis, complex salts act as catalysts, facilitating chemical reactions by providing an active site for the reaction to occur. In materials science, complex salts are utilized to create novel materials with unique properties, such as magnetic or luminescent characteristics.

Double salts also have diverse applications across different industries. In agriculture, double salts are used as fertilizers, providing essential nutrients to plants. In the food industry, double salts are employed as food additives, enhancing flavor and preserving food products. Double salts are also utilized in the production of dyes, pigments, and pharmaceuticals, where their distinct properties contribute to the desired end products.


Complex salt and double salt are two distinct types of salts with their own unique attributes. Complex salts are formed through the combination of a metal ion and ligands, resulting in coordination compounds with complex crystal structures. On the other hand, double salts are formed by the combination of two different salts, retaining their individual chemical formulas and crystal structures. Complex salts exhibit higher melting and boiling points, while double salts have lower melting and boiling points. Both types of salts find applications in various industries, contributing to fields such as medicine, catalysis, agriculture, and materials science. Understanding the attributes of complex salt and double salt allows us to appreciate their significance and potential in different areas of our lives.

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