Setting Fire to Glass - Chlorine Trifluoride
First discovered back in the 1930s, chlorine trifluoride is a rather curious chemical that
easily reacts, sometimes explosively, with just about every known substance on Earth.
Just to get the ball rolling, here’s a few of the more unusual things chlorine trifluoride
is known to set fire to on contact: glass, sand, asbestos, rust, concrete, people, pyrex,
cloth, and the dreams of children…
Obviously the first question to answer here is how chlorine trifluoride is somehow able
to cause asbestos, a substance that is known for being almost completely fire retardant,
to catch on fire.
Well, that’s because chlorine trifluoride is a more powerful oxidizing agent by mass
than oxygen itself.
Meaning it’s capable of rapidly oxidizing things that would normally be considered practically
“impossible” to set aflame, like asbestos.
Chlorine trifluoride is such an effective oxidizer that it can even potentially set
fire to things that have seemingly already been burned up, like ash or spent charcoal.
The substance is so highly reactive that famously unreactive elements like platinum, osmium
and iridium will begin to corrode when they come into contact with it.
Notably tough elements like titanium and tungsten are also regarded as being wholly unsuitable
to storing the chemical because they set on fire as soon as they come into contact with
it.
The only known way to store chlorine trifluoride “safely”, which we use in the loosest
possible sense, is to put it inside of a sealed containers made of steel, iron, nickel or
copper which are able to contain the chemical safely if they’re first treated with flourine
gas.
This is because doing so will coat the metal in a thin fluoride layer, with which the chemical
won’t react.
However, if this layer is compromised in anyway, or the metal isn’t completely dry, chlorine
trifluoride will begin to react violently and cause the vessel to explode.
A few of the other things known to not react with chlorine trifluoride include nitrogen,
the inert gases and polychlorotrifluoroethylene.
Rather fortunately, chlorine trifluoride doesn’t react with air unless it happens to contain
a larger than average amount of water vapor.
Speaking of which, when chlorine trifluoride comes into contact with water, it will react
explosively with it and as a fun byproduct creates large amounts of dangerous gasses
such as hydrofluoric acid and hydrochloric acid.
Hydrofluric acid in particular is incredibly dangerous and along with being able to melt
things like glass and concrete, can permanently damage your lungs and eyes.
As if that wasn’t worrying enough, if you’re ever unlucky enough to get hydrofluric acid
on your skin, it doesn’t actually hurt until a few hours later.
After it has absorbed a bit, it starts destroying your nerves and bones and can ultimately cause
cardiac arrest when it gets into your blood stream.
In fact, in 1994 a lab technician in Australia accidentally spilled hydrofluric acid on his
lap and despite immediately executing safety procedures including hosing off, immersing
himself in a swimming pool, and later extensive medical care (including needing to have one
of his legs amputated), within two weeks of the accident, he was dead.
Unsurprisingly, the Nazis were really interested in the military applications of chlorine trifluoride.
After all, it’s a substance that reacts explosively with water (humans are largely
bags of water), and for those that don’t come in contact with it directly, there’s
the byproduct of the deadly gasses.
Further, there is really little one can do to put out the fires it causes directly other
than to let them burn off.
If you throw water on the source of the problem, it will get worse.
The reaction here also doesn’t require atmospheric oxygen to burn, so trying to use that method
of fire suppression won’t work either.
Though chlorine trifluoride was thankfully never used during combat, the Nazis did succeed
in creating several tons of the stuff in a secret facility known as the Falkenhagen Bunker
before it was captured by the Russians in 1944.
The Nazis working in the Falkenhagen Bunker referred to chlorine trifluoride simply as
“Substance N” or “N-Stoff” and were planning to store it inside specially designed
shells which could be used in battle.
According to reports released by the Soviets following WW2, Nazi trials involving substance
N were promising.
But, of course, the weapon was incredibly dangerous for those carrying it around too,
not just those they launch it at.
As an example of the kind of devastation chlorine trifluoride can have, you only need to consider
what happened when almost a ton of this stuff was accidentally spilled inside of a warehouse
in the 1950s.
According to eyewitness reports, the chemical burned straight through a foot of concrete
and three feet of gravel while simultaneously releasing a deadly cloud of gas containing
a cocktail of “chlorine trifluoride, hydrogen fluoride, chlorine and hydrogen chloride”
that corroded every surface it came into contact with.
After reading this you’re probably curious about what possible purpose this chemical
could serve that doesn’t involve trying to recreate a scene from a Michael Bay movie.
Well, due to the fact that chlorine trifluoride is such a great oxidizer, there have been
several attempts to use it as a low-cost, lightweight rocket fuel, starting with the
Nazis who tried to use it to propel torpedoes.
Of course, it’s so difficult to store safely that it’s generally considered not to be
worth the risk for this usage.
After all, while you’d need to use less fuel thanks to its extreme oxidizing capabilities,
if you had a rocket accident, you’d potentially be spewing tons of this stuff all over the
place with no real effective way to deal with the situation.
For instance, after studying and experimenting with this chemical for rocket use, rocket
scientist Dr. John D. Clark famously said about the best way to deal with potential
chlorine trifluoride rocket accidents- “I have always recommended a good pair of running
shoes.”
There are a couple other useful applications though.
For instance, it’s great for plasmaless cleaning of certain surfaces used in semiconductor
manufacturing and it also works well at cleaning uranium residue off of the walls of nuclear
power plants and removing built up oxides.