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The World's Strongest Acids: Like Fire and Ice

If you paid attention in chemistry class, you'd know not to mess around with sulfuric acid. Even at a fairly dilute concentration, it's about ten times more acidic than the contents of your stomach. You don't want to spill it on your skin.

But you probably never learned not to muck around with fluoroantimonic acid. For the record, you shouldn't. Based on the silvery-white metal antimony, with a pH of -31.3, it's 100,000 billion billion billion times more potent than stomach acid, and makes its rambunctious cousin sulfuric acid look as gentle as a vanilla milkshake with whipped cream and a cherry on top.

"You couldn't pick up a bottle of it because after it ate through the bottle, it would dissolve your hand," Sam Kean noted in his book The Disappearing Spoon. This begs a simple question: how is fluoroantimonic acid stored?

The answer, my friends, is the polymer that all fans of fried chicken know and love: polytetrafluoroethylene, more commonly known as Teflon. Thanks to its carbon-fluorine bonds -- the strongest single bond in organic chemistry -- Teflon is not only unreactive, hydrophobic, and "non-stick" (making it handy for frying food), but it's also immune to a host of corrosive superacids. Even its chemical structure resembles a fortified bulwark.

Teflon_structure.PNGTeflon could also contain the second* most powerful acid: carborane, and not just because of Teflon's super cool properties. Though the boron-based carborane has a peppy pH of -18, it's also exceedingly gentle, meaning noncorrosive. Like its fellow acids, carborane is incredibly willing to donate a proton (hydrogen atom without an electron) to other substances -- that's what defines the strength of an acid. But what's left afterwards, unlike with sulfuric acid or fluoroantimonic acid, is a very content and stable little set of atoms.

Once losing its proton, fluoroantimonic acid and most other strong acids ravage other substances, often by ripping electrons from their atoms. If the substance in question is your skin, the acid will often cleave the amide bonds of proteins and the ester groups in fats through a process called hydrolysis. Either way, these corrosive acids wreak havoc on anything they touch, like the Hulk going on a destruction spree after being spurned by his long-time girlfriend. The aforementioned carborane, on the other hand, doesn't throw a temper tantrum after losing its hydrogen.

shutterstock_123448000.jpg"...The boron cage forms one of the most stable molecules ever invented," Kean explains. "Its boron atoms share electrons so generously that it practically becomes helium."

Sadly, carborane is rather rare, and likely won't be making a wide appearance in chemistry classes anytime soon.

*Technically carborane is the world's strongest solo acid because fluoroantimonic acid is a mixture of antimony pentafluoride and hydrofluoric acid. 


Primary Source:
The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements, Sam Kean, 2010

(Image: Hulk Stamp via Shutterstock)


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