Sodium Azide is comprised of colorless crystals. Its formula is NaN3. While it is very soluble in water, if it is heated to >3000C the salt breaks down explosively into sodium and nitrogen. It is this property that led to its use in car collision air bags. If the salt is placed in contact with metals salt or solutions of the salt, it can form unstable/ explosive azides. Acidification of a solution, or the addition of acid to the salt itself, can also result in the production of highly toxic hydrazoic acid (HN3), which is a volatile, shock-sensitive explosive gas.
A solution of the salt in water is however an effective end of life drink. Quantities as small as 1gm will reliably end life.
The exact mechanism of toxicity of sodium azide is not fully understood. Two mechanisms of operation are suggested.
The production of nitric oxide with it’s effect on the central nervous system, carotid baroreceptors, potent vasodilation with associated blood pressure drop can explain the reported headache, nausea, tachycardia, and circulatory collapse. Although the dissolves salt is relatively tasteless, the salt is rapidly hydrolysed on contact with mucosa to hydrazoic acid which has some irritant effect in the throat, and at higher concentrations, the direct effect of azide on cytochrome oxidase can cause cellular asphyxia and death in those organs with the highest need for oxygen, such as the brain and heart.
The effect of ingesting sodium azide has been likened to the simultaneous ingestion of both nitrite and cyanide, although azide ingestion does not lead to significant blood discolouration or reduction in oxygen carrying ability, and the toxic metabolic effects do not respond to the treatment for cyanide poisoning.