Sciencemadness Discussion Board

What would catch fire at room temp on contact with air?

fugate - 9-3-2013 at 22:27

The other day I bought a couple lithium batteries, and got lithium from one of them safely. Very fun! I accidently shorted the other one so I threw it outside before it got too hot and spewed out the electrolyte. A couple days later (after it was cooled and depressurized) I decided to pry it open to see how different it was from the fresh one.

This is where it got interesting.

Unlike the fresh one, the shorted one smelled TERRIBLE (probably sulfur dioxide?). That was fine though because I was outside and I was expecting it. What I did not expect was that once I unrolled the core of the battery, it began heating up, smoking, and in seconds was flaming.

I won't be doing that again, I assure you.
But why did this happen? I've scoured the internet but haven't found any explanation. What was in the shorted battery that ignited when exposed to air? (Note: this did not happen with the fresh battery. The fresh battery didn't even give off much SO2, as I had been warned it would)

Help a fellow experimenter learn from a failure
Thanks!

I hope this is in the right topic. I put it here because this has to do with acquiring lithium. New user here, so just tell me if i need to move this

elementcollector1 - 9-3-2013 at 22:37

The sulfur smell: Iron sulfide in the battery core.
As for why it spontaneously lit, I'd imagine exposure to oxygen, water (or even nitrogen in lithium's case) may have caused a reaction. What the reaction was, I can't quite say.

fugate - 9-3-2013 at 22:53

Thank you, that was the lead I needed!
Apparently iron (II) sulfide is pyrophoric, meaning it pretty much just bursts into flames because it feels like it, as long as there is oxygen.

I'm still trying to figure out why this did not occur with the fresh battery.

As for the lithium, the flames weren't really bright and ultra-hot like lithium usually is. However, after the flames died out, I tested the ashes by putting them in water. No reaction, so obviously there was no Li metal or Li2O, because it would have reacted. I did a flame test on the ahses though and there was lithium's telltale violet flame, so it must have formed some kind of ionic compound.

[Edited on 10-3-2013 by fugate]

elementcollector1 - 9-3-2013 at 22:56

Strangely enough, I've never had this problem.
What was the weather like when the battery flared up?

fugate - 9-3-2013 at 23:31

ohio winter night, maybe like 35-40 degrees F. Not too humid i don't think. I was actually in a large garage when it lit up, and i took it out to let it die down. It's worth noting that the remains of the core (i covered it with a blanket so the whole thing didnt completely burn away) was pretty damp afterwards. I really don't think
2Li + 2H2O --> 2LiOH + H2 or
4Li + O2 --> 2Li2O
was happening here, but i could be wrong.

Endimion17 - 10-3-2013 at 06:06

Quote: Originally posted by fugate  
Thank you, that was the lead I needed!
Apparently iron (II) sulfide is pyrophoric, meaning it pretty much just bursts into flames because it feels like it, as long as there is oxygen.

I'm still trying to figure out why this did not occur with the fresh battery.

As for the lithium, the flames weren't really bright and ultra-hot like lithium usually is. However, after the flames died out, I tested the ashes by putting them in water. No reaction, so obviously there was no Li metal or Li2O, because it would have reacted. I did a flame test on the ahses though and there was lithium's telltale violet flame, so it must have formed some kind of ionic compound.

[Edited on 10-3-2013 by fugate]


FeS is not pyrophoric. Its chunks are used in Kipp's apparatus for producing H2S. They look like rusty pieces of graphite, but unlike graphite, they aren't greasy and soft.
It might be pyrophoric if it's prepared as a fresh ultrafine powder, I'm not sure, but the one inside lithium batteries is not like that.

I'd say there was a silent, smouldering, surface phase reaction in your battery which then turned big after lots of oxygen rushed inside. What exactly happened, I don't know.

bhattshivamm - 14-3-2013 at 03:36

i think it is FeS2 which is pyrophoric... not FeS (and both are entirely different compounds)

woelen - 14-3-2013 at 04:16

FeS2 is not pyrophoric. I have this chemical at high purity, in the form of crystals and in the form of powder. Actually, it is amazingly inert, much more so than FeS.

FeS2 is sometimes called 'fool's gold', because of its gold-like appearance, especially when it is in the form of larger pieces. Real gold is more yellow though, FeS2 has an appearance somewhat between gold and silver and it is much less dense.

elementcollector1 - 14-3-2013 at 07:39

Quote: Originally posted by woelen  
FeS2 is not pyrophoric. I have this chemical at high purity, in the form of crystals and in the form of powder. Actually, it is amazingly inert, much more so than FeS.

FeS2 is sometimes called 'fool's gold', because of its gold-like appearance, especially when it is in the form of larger pieces. Real gold is more yellow though, FeS2 has an appearance somewhat between gold and silver and it is much less dense.


Ah, the joys of iron pyrite. I have a few pieces as well, mostly obtained from rock shops and Boy Scout trading posts (for some reason, they seem to love the stuff).

I still think lithium was your culprit... Were the flames red?