Silver azide
Silver azide is the chemical compound with the formula Template:Chem2. 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.[1] The silver azide precipitates as a white solid, leaving sodium nitrate in solution.
X-ray crystallography shows that Template:Chem2 is a coordination polymer with square planar Template:Chem2 coordinated by four azide ligands. Correspondingly, each end of each azide ligand is connected to a pair of Template:Chem2 centers. The structure consists of two-dimensional Template:Chem2 layers stacked one on top of the other, with weaker Ag–N bonds between layers. The coordination of Template:Chem2 can alternatively be described as highly distorted 4 + 2 octahedral, the two more distant nitrogen atoms being part of the layers above and below.[2]
| File:Silver-azide-high-T-single-layer-3D-balls.png | File:Silver-azide-high-T-layer-stacking-3D-balls.png | File:Silver-azide-high-T-Ag-coordination-3D-balls-A.png | File:Silver-azide-high-T-N-coordination-3D-balls-B.png |
| Part of a layer | Layer stacking | 4 + 2 coordination of Template:Chem2 | 2 + 1 coordination of N in Template:Chem2 |
In its most characteristic reaction, the solid decomposes explosively, releasing nitrogen gas:
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.[3] Pure silver azide explodes at 340 °C, but the presence of impurities lowers this down to 270 °C.[4] This reaction has a lower activation energy and initial delay than the corresponding decomposition of lead azide.[5]
Safety
Template:Chem2, like most heavy metal azides, is a dangerous primary explosive. Decomposition can be triggered by exposure to ultraviolet light or by impact.[1] Ceric ammonium nitrate Template:Chem2 is used as an oxidising agent to destroy Template:Chem2 in spills.[4]
See also
References
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