Silver azide

Silver azide

Names
IUPAC name Silver(I) azide
Other names Argentous azide
Identifiers
CAS Number	13863-88-2  Y
3D model (JSmol)	Interactive image
ChemSpider	55601  Y
ECHA InfoCard	100.034.173
PubChem CID	61698
UNII	H85PJD8U4L  Y
CompTox Dashboard (EPA)	DTXSID70894852
InChI InChI=1S/Ag.N3/c;1-3-2/q+1;-1 Y Key: QBFXQJXHEPIJKW-UHFFFAOYSA-N Y 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
SMILES [Ag+].[N-]=[N+]=[N-]
Properties
Chemical formula	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
Crystal structure	Orthorhombic oI16 [1]
Space group	Ibam, No 72
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Very toxic, explosive
NFPA 704 (fire diamond)	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  YN ?) Infobox references

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

Structure and chemistry

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 N−3

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

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

• Silver nitride

References

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. Robert Matyas, Jiri Pachman (2013). Primary Explosives (1st ed.). Springer. p. 93. ISBN   978-3-642-28435-9.
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.
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. 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.