sbreheny
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White Phosphorus Close Call
Just wanted to share with everyone a close call I just had - either luck or Someone upstairs is watching out for me!
I had 2 grams of white phosphorus in a crimp-sealed vial filled with water. This vial was then inside an outer glass bottle (with no water in it), and
this was sitting on a wooden shelf along with a number of other reagents and solvents - some very flammable. This is in my lab which is in an enclosed
porch which is unheated (except for an electric space heater I use occasionally if I am going to be working there when it is cold).
At some point in the last few weeks, when the lab fell below freezing, the water in the crimped vial froze and broke open the vial, draining the water
off the WP and into the bottom of the larger, outer bottle.
The WP did not catch fire. I suppose that maybe it never dried out enough or maybe there was insufficient oxygen in the bottle. If it had caught fire
and cracked the glass, it could have caused a major fire by spreading through the cabinet to the flammable solvents.
Several lessons learned - put ALL of my flammable solvents in the flammables cabinet, store the WP away from anything flammable, do not allow the
water covering the WP to freeze!
I had thought through what items might freeze in the lab and since all aqueous solutions dilute enough to freeze at the temperatures in there were
stored in partially-empty plastic containers, I didn't see a problem, but I forgot about the WP being stored under water!
Sean
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Magpie
lab constructor
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Thanks for posting this. I have much the same situation only I have ~12g of WP. There is a risk that the water will freeze but fortunately it
doesn't get quite cold enough in my garage. I have the inner bottle in a secondary containment outer bottle having a tightly closed screwed cap. The
WP, if it did ignite, should quickly consume the oxygen in the outer container and therefore stop burning. The big IF here is will that fire go out
before the soda glass of the outer container cracks open due to the heat of the fire.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Molecular Manipulations
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Well in my experience with WP (which isn't much, truth be told), it doesn't catch fire even at room temperature in 21% oxygen. And I'm sure at
sub-zero temps it definitely wouldn't. It would probably react slowly with the oxygen in the bottle, release a little heat, and then stop.
Not trying to undermine the dangers of the stuff, but you'd have to be quite unlucky to have WP catch fire while moist with ice at below
zero.
Now if it did catch, you'd have to be quite lucky for it not crack the soda-lime glass and catch nearby flammables on fire. So yeah, store it away
from other flammables for sure.
-The manipulator
We are all here on earth to help others; what on earth the others are here for I don't know. -W. H. Auden
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Dan Vizine
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White P is not as much of a treacherous beast as many think. I should add "until it finally ignites".
I have a thread on this site which shows my attempts to let about 2 1/2 g WP spontaneously ignite. It was a moderate summer day, maybe 75 degrees. I
placed the sample on a large flat rock. It changed over many minutes, looked a bit mushy, but no flames.
Thinking the rock was too efficient a heat sink, I moved it to a wooden log. A minute or two later, it rapidly inflamed and acquired a viscosity so
low, the fire looked like gasoline burning as it flowed extremely easily to cover an area maybe a hundred times the original footprint.
If the white P is melted in an inert gas or under water first, and then O2 finds it, the fire is fast and furious.
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
Deserve"...F. Zappa
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Deathunter88
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Quote: Originally posted by Dan Vizine  | White P is not as much of a treacherous beast as many think. I should add "until it finally ignites".
I have a thread on this site which shows my attempts to let about 2 1/2 g WP spontaneously ignite. It was a moderate summer day, maybe 75 degrees. I
placed the sample on a large flat rock. It changed over many minutes, looked a bit mushy, but no flames.
Thinking the rock was too efficient a heat sink, I moved it to a wooden log. A minute or two later, it rapidly inflamed and acquired a viscosity so
low, the fire looked like gasoline burning as it flowed extremely easily to cover an area maybe a hundred times the original footprint.
If the white P is melted in an inert gas or under water first, and then O2 finds it, the fire is fast and furious. |
I agree, white phosphorus doesn't seem to burn very readily unless it is in its molten state. I once tried to have a piece ignite spontaneously but it
was in the middle of winter and no matter what I did it would not ignite on its own. It was when I used a lighter that it finally caught fire and
burned viciously.
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