[paul cotter (OP)]

I purchased 500gr of sodium azide(£80 at the time-ouch!) about 45years ago and have used only about 10gr in that time. I have always kept it well sealed and safely stored but I still worry about moisture ingress and possible hydrolysis with it's age. I have never detected any aroma on opening the container(hn3 smells really bad). A lot of sodium salts are hygroscopic or even deliquescent, certainly compared to their potassium counterparts.      Very late edit: I have looked extensively myself for this info myself, in vain.

[Zer0]

If it's still white & odourless then all seems well.

Online it says that NaN3 burns in air & can explode too.

Perhaps it's high time you put it away Safely.

P.S. - Chemistry is equally interesting & utterly scary at the same time.
🤞

[paul cotter (OP)]

Not really explosive but it will burn erratically. If heated strongly it suddenly decomposes in to metallic sodium and nitrogen but not explosively. Most other metal azides are more dangerous, the lead salt detonates violently and is one of the few explosives that cannot be ignited without detonation occurring( common explosives ).  Late edit: it is also highly toxic, binding one of the cytochromes( can't remember which one ) in a manner similar to cyanide.

[Zer0]

Cytochrome C Oxidase.

[paul cotter (OP)]

In addition, it was widely used in automotive airbags, together with an oxidiser to deal with the sodium produced. It may still be used but there were concerns about it's toxicity considering a bag containing 100gr could potentially kill several hundred people if disassembled live.

[hiediarreola]

Watch out with it. If it catches fire you’re in deep sh1t. I don’t even know how you would put it out. Water is obviously a no no. Sand will make a thermite. CO2 might just work. Scary toxic. Acid liberates HN3 Salts of azide are very explosive. CuN3 startled the sh1t out of me and i vaguely remember a story of a uni kid losing some digits because of it.

The lethal dose would be about 200mg I think, but even 20mg could be really bad.(correct me if I’m wrong about any of this)

[paul cotter (OP)]

ld50 more like 500-1000mg. Not quite as toxic as sodium cyanide( ~300mg ) despite having a similar toxic mechanism. It might produce a more prolonged toxicity: cyanide is rapidly detoxified by rhodanase( ? ) if fatality has been avoided, i'm not aware of any similar azide detox. Cuprous azide is known to be very sensitive. There is also cupric azide, Cun6, which I imagine would be more aggressive but it starts decomposing quickly after preparation into a black mess of Cun3, Cu, N2