Lead(II) azide

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Lead(II) azide
Lead(II) azide by Explosiopedia.jpg
Lead(II) azide powder
Names
IUPAC name
Diazidolead
Other names
Lead azide
Bleiazid
Properties
Pb(N3)2
Molar mass 291.24 g/mol
Appearance White powder
Odor Odorless
Density 4.71 g/cm3
Melting point 190 °C (374 °F; 463 K) (decomposes)
Boiling point (explodes at 350 °C)
2.3 g/100 mL (18 °C)
9.0 g/100 mL (70 °C)
Solubility Very soluble in acetic acid
Slightly soluble in alcohol and ether
Insoluble in aqueous ammonia
Thermochemistry
462.3 kJ/mol
Hazards
Safety data sheet CPCB
Related compounds
Related compounds
Sodium azide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Lead azide is an inorganic compound with the formula Pb(N3)2. It is used as a primer in detonators to initiate secondary explosives, though it has been removed from most commercial detonators due to its toxicity.

Properties

Chemical

Gently heating lead(II) azide will give off nitrogen gas and leave behind pure lead. However, the decomposition is not as smooth as that of sodium azide, and may explode. If the decomposition takes place in air, lead(II) oxide will also form.

Physical

Lead azide is a white solid, poorly soluble in water and ammonia, but very soluble in acetic acid, more so if hot. It has a density of 4.71 g/cm3. Lead(II) azide decomposes at 190 °C and explodes if heated at higher temperatures.

Explosive

Lead(II) azide is very sensitive to shock and friction and can be easily set off by a strong impact or an open flame. Its detonation velocity is 5180 m/s.

Carbon dioxide increases its sensitivity, especially in the presence of moisture, by forming carbonic acid.

Availability

Lead(II) azide is not sold even by big chemical suppliers. Explosive companies will sell Pb(N3)2 detonators, but only if you have an explosive permit.

Preparation

Lead(II) azide can be prepared by adding an aqueous solution of lead(II) nitrate to a solution of sodium azide.

Pb(NO3)2 + 2 NaN3 → Pb(N3)2 + 2 NaNO3

Due to its low solubility, lead azide precipitates out of the solution. The precipitate is filtered, washed with anhydrous ethanol and air dried.[1]

Dextrin is generally added as a stabilizer during synthesis, to inhibit the formation of large or needle-like crystals, which are very sensitive. Other compounds, like polyvinyl alcohol (PVA) can also be used.

Lead(II) acetate can also be used instead of the nitrate.

Projects

  • Make blasting caps

Handling

Safety

Lead(II) azide is very toxic and should be handled with proper protection.

Lead azide can react with copper, zinc, cadmium to form their respective azides, which are even more sensitive. Contact with these metals must be avoided. Aluminium however does not react with Pb(N3)2 due to the formation of an oxide layer.

Storage

Lead(II) azide is best stored in rubber or wood containers, to avoid static discharges. Plastic or glass containers may not be suitable. Dextrin is used as a stabilizer.

Disposal

Nitrous acid can be used to destroy lead(II) azide. Ammonium acetate and sodium dichromate can also be used.

References

  1. http://www.lambdasyn.org/synfiles/bleiazid.htm

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