Lead azide is an explosive and
toxic crystalline compound frequently used in primers, blasting caps,
and fuses. Lead azide is sensitive to heat, shock and friction. The velocity of detonation is
approximately 17,500 feet /second. Its color varies from white to buff. It is not very hygroscopic,
but when properly protected from moisture it will not suffer a decrease in performance and can be
stored for long periods of time. Water does not reduce its impact sensitivity. When protected from
humidity, is completely stable in storage.
IUPAC NAME: lead (II) azide
MOLECULAR FORMULA: Pb(N3)2
MOLAR MASS: 291.2402 g/mol
SHOCK SENSITIVITY: High
FRICTION SENSITIVITY: High
EXPLOSIVE VELOCITY: 5180 m/s
Lead azide is poisonous, slightly soluble in hot water and in alcohol, and highly soluble in a
diluted solution of nitric or acetic acid in which a little sodium nitrate has been dissolved. It
reacts with copper, zinc, cadmium, or alloys containing such metals, forming an azide that is more
sensitive than the original lead tide.
Lead azide will react with common metals, except aluminum, producing azide salts that are unstable. Aluminum is the metal of choice for any container that will house lead azide.
Lead azide is currently the most commonly used primary explosive, but because of the toxicity of lead it is being phased out.
Lead azide is prepared by metathesis between sodium azide and lead nitrate or lead dissolved in nitric acid. Dextrose can be added to the solution to stabilize the product. The addition of dextrin to lead azide in this preparation prevents the formation of large crystals which can be very dangerous.