Ammonium nitrate is an ionic salt made up of the ammonium cation (NH4)+ and the nitrate anion (NO3)–. The chemical formula of this compound is NH4NO3. Ammonium nitrate readily dissolves in water by dissociating into its constituent ions. This salt is acidic in nature since it is derived from a weak base (NH3) and a strong acid (HNO3).
NH4NO3 can be prepared from the acid-base reaction between nitric acid and ammonia, described by the following chemical equation:
NH3 + HNO3 → NH4NO3
This reaction is highly exothermic and proceeds in a violent fashion. Ammonium nitrate is also known for its oxidizing powers. It is widely used in many explosives used in the mining and construction sectors. NH4NO3 is also one of the key components of ANFO, one of the most popular choices of industrial explosives.
This compound features an ionic bond between an ammonium ion and a nitrate ion. The structure of an NH4NO3 molecule is illustrated below.
Ammonium Nitrate Structure
The pi electrons in the nitrate ion are delocalized due to resonance. The net charge on this ion is -1 (since the nitrogen atom holds a charge of +1 and each oxygen atom holds a charge of -⅔). Therefore, only one NH4+ ion can form an ionic bond with one NO3– ion.
|Molar Mass/ Molecular Weight||80.043 grams per mole|
|Density||1.725 grams per cubic centimetre|
|Melting Point||442.8K (169.6oC)|
|Boiling Point||Decomposes at 483K (210oC)|
Some of the important applications of this ionic salt are listed below.
Despite its numerous applications, the use of this compound is being slowly phased out by the governments of many countries due to its scope for misuse.