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Silver azide

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Silver azide
Silver-azide-high-T-single-layer-3D-vdW.png
Names
IUPAC name
Silver(I) azide
Other names
Argentous azide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.034.173
PubChem CID
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
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 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

Silver azide can be prepared by treating an aqueous solution of silver nitrate with sodium azide. 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.

Silver-azide-high-T-single-layer-3D-balls.png Silver-azide-high-T-layer-stacking-3D-balls.png Silver-azide-high-T-Ag-coordination-3D-balls-A.png Silver-azide-high-T-N-coordination-3D-balls-B.png
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. Pure silver azide explodes at 340 °C, but the presence of impurities lowers this down to 270 °C. This reaction has a lower activation energy and initial delay than the corresponding decomposition of lead azide.

Safety

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

See also


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