Ammonium nitrite

Ammonium nitrite

Identifiers
CAS Number	13446-48-5 Y
3D model (Jmol)	Interactive image
ChemSpider	24223 Y
ECHA InfoCard	100.033.257
InChI InChI=1S/HNO2.H3N/c2-1-3;/h(H,2,3);1H3 Y Key: CAMXVZOXBADHNJ-UHFFFAOYSA-N Y InChI=1/HNO2.H3N/c2-1-3;/h(H,2,3);1H3 Key: CAMXVZOXBADHNJ-UHFFFAOYAU
SMILES [O-]N=O.[NH4+]
Properties
Chemical formula	NH4NO2
Molar mass	64.06 g/mol
Appearance	pale yellow crystals, slowly decomposes to nitrogen and water
Density	1.69 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Ammonium nitrite, NH₄NO₂, is the ammonia 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.

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, but 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. A safe pH can be maintained by adding an ammonia solution. The mole ratio of ammonium nitrite to ammonia must be above 10%.

NH₄NO₂ → N₂ + 2 H₂O

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.

References