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Silver azide

From Wikipedia, the free encyclopedia
Silver azide
Names
IUPAC name
Silver(I) azide
Other names
Argentous azide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.034.173 Edit this at Wikidata
UNII
  • InChI=1S/Ag.N3/c;1-3-2/q+1;-1 checkY
    Key: QBFXQJXHEPIJKW-UHFFFAOYSA-N checkY
  • InChI=1/Ag.N3/c;1-3-2/q+1;-1
    Key: QBFXQJXHEPIJKW-UHFFFAOYAJ
  • InChI=1S/Ag.N3/c;1-3-2/q+1;-1
    Key: QBFXQJXHEPIJKW-UHFFFAOYSA-N
  • [Ag+].[N-]=[N+]=[N-]
Properties
AgN3
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
Structure
Orthorhombic oI16[1]
Ibam, No 72
Hazards
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
3
0
4
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

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.

Structure and chemistry

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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

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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

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References

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  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.