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 a 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