# Ammonium nitrite

Ammonium nitrite, NH4NO2, is the ammonium salt of nitrous acid. It is not used in pure isolated form since it is highly unstable and decomposes into water and nitrogen, even at room temperature.

Identifiers Properties CAS Number 13446-48-5 3D model (JSmol) Interactive image ChemSpider 24223 ECHA InfoCard 100.033.257 EC Number 236-598-7 PubChem CID 26004 UNII 71ZQG69956 CompTox Dashboard (EPA) InChI InChI=1S/HNO2.H3N/c2-1-3;/h(H,2,3);1H3 Key: CAMXVZOXBADHNJ-UHFFFAOYSA-N InChI=1/HNO2.H3N/c2-1-3;/h(H,2,3);1H3Key: CAMXVZOXBADHNJ-UHFFFAOYAU SMILES [O-]N=O.[NH4+] Chemical formula NH4NO2 Molar mass 64.06 g/mol Appearance pale yellow crystals, slowly decomposes to nitrogen and water Density 1.69 g/cm3 Melting point Decomposes Solubility in water 118.3 g / 100mL Shock sensitivity Low Friction sensitivity Low Detonation velocity >1000 m/s Main hazards Explosive GHS pictograms GHS Signal word Danger NFPA 704 (fire diamond) Flash point Non-flammable Autoignitiontemperature Non-flammable Other anions Ammonium nitrate Other cations Sodium nitrite Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

## Preparation

Ammonium nitrite forms naturally in the air and can be prepared by the absorption of equal parts nitrogen dioxide and nitric oxide in aqueous ammonia.[1]

It can also be synthesized by oxidizing ammonia with ozone or hydrogen peroxide, or in a precipitation reaction of barium or lead nitrite with ammonium sulfate, or silver nitrite with ammonium chloride, or ammonium perchlorate with potassium nitrite. The precipitate is filtered off and the solution concentrated. It forms colorless crystals which are soluble in water.

## Physical and chemical properties

Ammonium nitrite may explode at a temperature of 60–70 °C,[1] and will decompose quicker when dissolved in a concentrated aqueous solution, than in the form of a dry crystal. Even in room temperature the compound decomposes into water and nitrogen;

${\displaystyle {\ce {NH4NO2 -> N2 + 2H2O}}}$

It decomposes when heated or in the presence of acid into water and nitrogen.[2] Ammonium nitrite solution is stable at higher pH and lower temperature. If there is any decrease in pH lower than 7.0, it may lead to an explosion, since the nitrite can react to it. A safe pH can be maintained by adding an ammonia solution. The mole ratio of ammonium nitrite to ammonia must be above 10%.

## References

1. Thomas Scott; Mary Eagleson (1994). Concise encyclopedia chemistry. Walter de Gruyter. p. 66. ISBN 3-11-011451-8.
2. "VIAS Encyclopedia: Ammonium Nitrite".