A few days ago I wrote about sodium azide, a nasty chemical that has been put to a nice use. As usual, io9 commenters one-upped me by bringing up dioxygen difluoride — also known as Satan's Kimchi, or FOOF. Learn all about the chemical that requires you risk life and limb just to synthesize it.

Dioxygen difluoride is made up of two fluorine atoms and two oxygen atoms - earning it the nickname FOOF. It sounds simple, but fluorine isn't an easy chemical to work with under any circumstances, and it can't be forced into this particular combination without a 700 degree heating block.

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As monumental as this seems, it was done by a man named A. G. Streng, all the way back in 1932, when life was cheap among chemists. The blog Things I Won't Work With, which dubs dioxygen difluoride "Satan's kimchi," describes what happens when it combines with anything.

" The great majority of Streng's reactions have surely never been run again. The paper goes on to react FOOF with everything else you wouldn't react it with: ammonia ("vigorous", this at 100K), water ice (explosion, natch), chlorine ("violent explosion", so he added it more slowly the second time), red phosphorus (not good), bromine fluoride, chlorine trifluoride (say what?), perchloryl fluoride (!), tetrafluorohydrazine (how on Earth. . .), and on, and on. If the paper weren't laid out in complete grammatical sentences and published inJACS, you'd swear it was the work of a violent lunatic. I ran out of vulgar expletives after the second page."

I highly recommend you read the whole piece as it gives you a perspective on why FOOF is the chemical equivalent of a chestburster — perfectly engineered to kill. I can't improve on it except to say that I found out that FOOF is copper red to straw yellow, that it can be made at a rate of six grams an hour, and that it makes "ping" sounds when it drips on uncooled lab equipment.

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This, interestingly, contradicts what urban dictionary has to say about FOOF, which is that it makes "foof" sounds whenever it reacts to things. (Update that, guys!) It's understandable the the etymology is a bit lax, as dioxygen difluoride is only the third most popular definition for FOOF, after "a much less vulgar word . . . for the female genital area," and "a silent but deadly form of flatulence." So if someone offers you FOOF, have them clarify, because you do not want to get a vagina, a fart, and dioxygen difluoride mixed up.

Top Image: Daria

[Sources: I Won't Work With Dioxygen Difluoride, Direct Synthesis of Liquid Dioxygen Difluoride, Urban Dictionary.]