Difference Between Double Salt and Complex Salt

Main Difference

The main difference between double salt and complex salt is that double salt is a mixture of two salt compounds, whereas complex salt has a molecular structure that is the combination of one or more complex ions.

Double Salt vs. Complex Salt

A double salt is a compound formed by the mixture of two different salt compounds, whereas a complex salt is a compound formed of a central metal atom having coordination bonds with ligands around it. A double salt in water completely dissociates into its ions while complex salt in water does not dissociate into its ions completely. Double salt, when added to water, gives simple ions; on the other hand, complex does not give simple ions when added to water. Double salt can easily be analyzed by determining the ions present in the aqueous solution; on the contrary, by determining the ions present in the aqueous solution, complex salt cannot be easily analyzed. Double salt contains two simple salts in equal proportions; conversely, complex salt from which it is formed may or may not be in the equimolar proportions. Double salt exists only in the solid state because, in aqueous solution, it dissociates completely into its ions, whereas complex salt exists both in solid or in the aqueous state. Double salt loses its identity as salt in aqueous solution while complex salt retains its identity even in the aqueous solution. The metal ions show their normal valency in a double salt; on the flip side, the metal ion satisfies its two types of valencies called primary and secondary valencies in a complex salt.

Comparison Chart

Double SaltComplex Salt
A double salt is a compound formed by the combination of two different salt compounds.A complex salt is a compound formed of a central metal atom having coordination bonds with ligands around it.
Dissociation
Completely dissociates into its ionsDoes not dissociate into its ions completely
Resulting Ions
Gives simple ionsDoes not give simple ions
Analysis
Can easily be analyzedCannot be easily analyzed
Proportion of Salts
Contains two simple salts in equal proportionsMay or may not be in the equimolar proportions.
State
Exists only in the solid-stateExists both in solid or in an aqueous state
Identity in Aqueous Solution
Loses its identity as a saltRetains its identity even in the aqueous solution
Metal Ions
Show their normal valencyMetal ion satisfies its two types of valencies called primary and secondary valencies
Example
Mohr’s salt; FeSO4.(NH4)2SO4.6H20K2(NiCl4)

What is Double Salt?

A double salt is a compound formed by the combination of two different salt compounds. Therefore, double salt is formed of more than one cation and anion and by dissolving the salt compounds in the same liquid, followed by crystallization in a regular pattern resulting in the formation of the double salt. Double salt dissociates completely into its ions when dissolved in water, and this dissociation produces simple ions in the aqueous solution because this solution was composed of cations and anions which were in the initial two salt compounds. When preparing a double salt, it should contain these two simple salts in equal proportions otherwise a uniform, and regular lattice cannot be obtained. The properties of these crystals are different from the properties of initial salts which were used in the preparation of double salt. Double salt can easily be analyzed by determining the ions present in the aqueous solution, due to its complete dissociation in water.

Examples

Tutton’s salt, Alums, Bromlite, Potassium sodium tartrate, etc.

What is Complex Salt?

A complex salt is a compound formed of a central metal atom having coordination bonds with ligands around it. There are present cations and anions bonded to each other, that’s why this compound is also called a complex salt due to complex structure. Complex salt in water does not dissociate into its ions completely but remain as a complex structure. In the chelation of metal ions, this complex formation is helpful. The metal ion satisfies its two types of valencies called primary and secondary valencies in a complex salt. Complex salt from which it is formed may or may not be in the equimolar proportions. Complex salt exists both in solid or in the aqueous state because it does not dissociate into its ions in aqueous solution. Complex salt retains its identity even in the aqueous solution.

Key Differences

  1. A double salt is a compound formed by the combination of two different salt compounds, whereas a complex salt is a compound formed of a central metal atom having coordination bonds with ligands around it.
  2. A double salt in water completely dissociates into its ions while complex salt in water does not dissociate into its ions completely.
  3. Double salt, when added to water, gives simple ions; on the other hand, complex does not give simple ions when added to water.
  4. Double salt can easily be analyzed by determining the ions present in the aqueous solution; on the contrary, by determining the ions present in the aqueous solution, complex salt cannot be easily analyzed.
  5. Double salt contains two simple salts in equal proportions; conversely, complex salt from which it is formed may or may not be in the equimolar proportions.
  6. Double salt exists only in the solid state because, in aqueous solution, it dissociates completely into its ions, whereas complex salt exists both in solid or in the aqueous state.
  7. Double salt loses its identity as salt in aqueous solution while complex salt retains its identity even in the aqueous solution.
  8. The metal ions show their normal valency in a double salt; on the flip side, the metal ion satisfies its two types of valencies called primary and secondary valencies in a complex salt.

Conclusion

Above discussion concludes that double salt is a mixture of two salt compounds, whereas complex salt has a molecular structure that is the combination of one or more complex ions.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

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