The Chemistry of Powder and Explosives - Sciencemadness Dot Org

LEAD AZIDE 429
of which there extends a horizontal shaft equipped with teeth.
The air in the apparatus is displaced with ammonia gas, the
autoclave is heated to about 230°, and nitrous oxide is passed in
while the horizontal stirrer is rotated. The nitrous oxide reacts
with one equivalent of sodamide to fonn sodium azide and water.
The water reacts with a second equivalent of sodamide to fonn
sodium hydroxide and ammonia.
NaNH2 + N,0 > NaN3 + H2O
NaNHj + H2O > NaOH + NH3
The reaction is complete when no more ammonia is evolved. The
product, which consists of an cquhnoleeular mixture of sodium
hydroxide and sodium azide, may be taken up in water and
neutralized carefully with nitric acid, and the resulting solution
may be used directly for the preparation of lead azide, or the
product may be fractionally crystallized from water for the production
of sodium azide. The same material may be procured by
washing the product with warm alcohol which dissolves away the
sodium hydroxide.
The different methods by which hydrazoic acid and the azides
may be prepared indicate that the acid may properly be represented
by any one or by all of the following structural formulas.
H—N/ I H—N< || H—N=N=N
Hydrazoic acid is a weak acid; its ionization constant at 25°,
1.9 X 10" 5 , is about the same as that of acetic acid at 23°,
1.86 X 10" 5 . It dissolves zinc, iron, magesium, and aluminum,
fonning azides with the evolution of hydrogen and the production
of a certain amount of ammonia. It attacks copper, silver, and
mercury, forming azides without evolving hydrogen, and is reduced
in part to ammonia and sometimes to hydrazinc and free
nitrogen. Its reaction with copper, for example, is oluscly analogous
to the reaction of nitric acid with that metal.
Cu + 3HN3
3Cu + 8HNO3
> Cu(N3), + Ns + NH3
> 3Cu(NO3)2 + 2NO + 4H O
So also, like nitric acid, it oxidizes hydrogen sulfide with the
liberation of sulfur.