Silver azide


Silver azide is the chemical compound with the formula AgN3. It is a silver(I) salt of hydrazoic acid. It forms a colorless crystals. Like most azides, it is a primary explosive.

Silver azide
IUPAC name
Silver(I) azide
Other names
Argentous azide
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3D model (JSmol)
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ECHA InfoCard 100.034.173 Edit this at Wikidata
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  • DTXSID70894852 Edit this at Wikidata
  • InChI=1S/Ag.N3/c;1-3-2/q+1;-1 checkY
  • InChI=1/Ag.N3/c;1-3-2/q+1;-1
  • InChI=1S/Ag.N3/c;1-3-2/q+1;-1
  • [Ag+].[N-]=[N+]=[N-]
Molar mass 149.888 g/mol
Appearance colorless crystals
Density 4.42 g/cm3
Melting point 250 °C (482 °F; 523 K) explosive
Boiling point decomposes
Solubility in other solvents 2.0×10−8 g/L
Orthorhombic oI16[1]
Ibam, No 72
Occupational safety and health (OHS/OSH):
Main hazards
Very toxic, explosive
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 4: Readily capable of detonation or explosive decomposition at normal temperatures and pressures. E.g. nitroglycerinSpecial hazards (white): no code
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

Structure and chemistry edit

Silver azide can be prepared by treating an aqueous solution of silver nitrate with sodium azide.[2] The silver azide precipitates as a white solid, leaving sodium nitrate in solution.

AgNO3(aq) + NaN3(aq) → AgN3(s) + NaNO3(aq)

X-ray crystallography shows that AgN3 is a coordination polymer with square planar Ag+ coordinated by four azide ligands. Correspondingly, each end of each azide ligand is connected to a pair of Ag+ centers. The structure consists of two-dimensional AgN3 layers stacked one on top of the other, with weaker Ag–N bonds between layers. The coordination of Ag+ can alternatively be described as highly distorted 4 + 2 octahedral, the two more distant nitrogen atoms being part of the layers above and below.[3]

Part of a layer Layer stacking 4 + 2 coordination of Ag+ 2 + 1 coordination of N in N3

In its most characteristic reaction, the solid decomposes explosively, releasing nitrogen gas:

2 AgN3(s) → 3 N2(g) + 2 Ag(s)

The first step in this decomposition is the production of free electrons and azide radicals; thus the reaction rate is increased by the addition of semiconducting oxides.[4] Pure silver azide explodes at 340 °C, but the presence of impurities lowers this down to 270 °C.[5] This reaction has a lower activation energy and initial delay than the corresponding decomposition of lead azide.[6]

Safety edit

AgN3, like most heavy metal azides, is a dangerous primary explosive. Decomposition can be triggered by exposure to ultraviolet light or by impact.[2] Ceric ammonium nitrate [NH4]2[Ce(NO3)6] is used as an oxidising agent to destroy AgN3 in spills.[5]

See also edit

References edit

  1. ^ Marr H.E. III.; Stanford R.H. Jr. (1962). "The unit-cell dimensions of silver azide". Acta Crystallographica. 15 (12): 1313–1314. Bibcode:1962AcCry..15.1313M. doi:10.1107/S0365110X62003497.
  2. ^ a b Robert Matyas, Jiri Pachman (2013). Primary Explosives (1st ed.). Springer. p. 93. ISBN 978-3-642-28435-9.[1]
  3. ^ Schmidt, C. L. Dinnebier, R.; Wedig, U.; Jansen, M. (2007). "Crystal Structure and Chemical Bonding of the High-Temperature Phase of AgN3". Inorganic Chemistry. 46 (3): 907–916. doi:10.1021/ic061963n. PMID 17257034.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ Andrew Knox Galwey; Michael E. Brown (1999). Thermal decomposition of ionic solids (vol.86 of Studies in physical and theoretical chemistry. Elsevier. p. 335. ISBN 978-0-444-82437-0.
  5. ^ a b Margaret-Ann Armour (2003). Hazardous laboratory chemicals disposal guide, Environmental Chemistry and Toxicology (3rd ed.). CRC Press. p. 452. ISBN 978-1-56670-567-7.
  6. ^ Jehuda Yinon; Shmuel Zitrin (1996). Modern Methods and Applications in Analysis of Explosives. John Wiley and Sons. pp. 15–16. ISBN 978-0-471-96562-6.