Here's why:
* Ammonium ion is a small, highly charged cation: This makes it strongly attracted to anions in solution, leading to strong ionic bonds.
* Ionic compounds with ammonium are generally soluble: The strong attraction between ammonium and anions overcomes the forces holding the ions together in the crystal lattice, making the salts readily dissolve in water.
Exceptions:
While most ammonium salts are soluble, a few notable exceptions exist:
* Ammonium hexachloroplatinate(IV) [(NH₄)₂[PtCl₆]]: This salt is yellow, crystalline, and relatively insoluble in water. It was historically used in the analysis of potassium ions.
* Ammonium tetraphenylborate [(NH₄)[B(C₆H₅)₄]]: This compound is also relatively insoluble in water. It's used in analytical chemistry to precipitate potassium and other large cations.
Key Point:
The solubility of ammonium salts is generally high, making them readily soluble in water. The few exceptions are mainly specific, complex salts used for analytical purposes.
