Ammonium azide

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Ammonium azide
Names
IUPAC name
Ammonium azide
Other names
Ammonium trinitride
Azanium azide
Properties
NH4N3
Molar mass 60.059 g/mol
Appearance White crystalline solid
Odor Odorless
Density 1.3459 g/cm3 (at 20 °C)
Melting point 160 °C (320 °F; 433 K)
Boiling point 400 °C (752 °F; 673 K) (decomposes)
Poorly soluble
Solubility Soluble in anh. ammonia
Vapor pressure 0.2 mmHg (at 15 °C)[1]
Thermochemistry
113.2 - 115 kJ·mol−1
140.4 - 142.3 kJ·mol−1[2]
Hazards
Related compounds
Related compounds
Sodium azide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Ammonium azide is the an explosive chemical compound with the formula NH4N3.

Ammonium azide is one of the few oxygen-free explosive materials that can be handled (relative) safely.

Properties

Chemical

Ammonium azide will detonate to release nitrogen and hydrogen gases.

NH4N3 → 2 N2 + 2 H2

Traces of ammonia are also produced.

Physical

Ammonium azide is a non-hygroscopic colorless odorless crystalline solid. It melts at 160 °C and decomposes at 400 °C. Ammonium azide is poorly soluble in water, but soluble in ammonia. It is also easily soluble in ethanol, glycerol, methanol, pyridine, sparingly soluble in allyl alcohol, butanol and isobutanol and insoluble in acetone, aniline, benzaldehyde, benzene, carbon disulfide, chlorobenzene, chloroform, diethyl ether, ethyl acetate, isoamyl alcohol, methyl acetate, methyl ethyl ketone, nitrobenzene, tetrachloroethane, toluene and xylene.[3]

Explosive

Ammonium azide has relative low shock sensitivity and is stable when heated to drying at 100 °C.[4] Strong heating will cause it to break down to ammonia and hydrazoic acid, the latter being the one that detonates. Due to its low shock sensitivity, ammonium azide can be safely ground in a wooden mortar.[5] It will also detonate under strong shock and in contact with some metals, such as copper.

Availability

Ammonium azide is not sold and has to be made.

Preparation

Ammonium azide can be made by bubbling anhydrous ammonia in a ether solution of HN3. Since ammonium azide is almost insoluble in ether, it will precipitate. The precipitate is filtered and vacuum dried. Water traces are removed using phosphorus pentoxide in a desiccator.

Heating a mixture of sodium azide with ammonium nitrate in a stream of dry air in a tube at 190 °C for 30 min will yield ammonium azide. The yield of the process is 93%. Ammonium sulfate can also be used instead of nitrate.[6]

Projects

  • Make exotic azides

Handling

Safety

Ammonium azide is explosive and toxic.

Storage

Should only be stored in closed bottles in cold places for short periods of time, as it will slowly sublime away.

Disposal

Can be neutralized with nitrous acid.

References

  1. Frost; Cothran; Browne; Journal of the American Chemical Society; vol. 55; (1933); p. 3516
  2. Finch, Arthur; Gardner, P. J.; Head, A. J.; Xiaoping, Wu; Journal of Chemical Thermodynamics; vol. 22; nb. 3; (1990); p. 301 - 305
  3. Frost; Cothran; Browne; Journal of the American Chemical Society; vol. 55; (1933); p. 3516
  4. Reckeweg, Olaf; Simon, Arndt; Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences; vol. 58; nb. 11; (2003); p. 1097 - 1104
  5. Yakovleva, G. S.; Kurbangalina, R. Kh.; Stesik, L. N. (1977), Combustion, Explosion, and Shock Waves, Detonation properties of ammonium azide, 13 (3), p. 405
  6. Frierson, W. J.; Browne, A. W.; Journal of the American Chemical Society; vol. 56; (1934); p. 2384

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