Question

What is the most powerful acid in the world?

Answer 1

The strongest acid I can find is fluoroantimonic acid.

Explanation:

Any acid stronger than 100 % pure sulfuric acid is a superacid.

Superacids are so powerful that we cannot use `"p"K_text(a)` values to measure their acidities.

Instead, we must use Hammett `H_0` values.

`H_0` is similar to `"p"K_text(a)` in that it is a logarithmic scale and a more negative value means a stronger acid.

Here is a table of some superacids.

`ulbb("Acid"color(white)(mmmmmm)"Structure"color(white)(mml)H_0color(white)(m))`
`("Sulfuric"color(white)(mmmmm)"H"_2"SO"_4color(white)(mmmml)"-12.0")`
`"Chlorosulfuric"color(white)(mml)"ClSO"_3"H"color(white)(mmmll)"-12.8"`
`"Triflic"color(white)(mmmmmml)"CF"_3"SO"_3"H"color(white)(mmll)"-14.1"`
`"Oleum"color(white)(mmmmmm)"H"_2"O"_4"·SO"_3color(white)(mmll)"-15"`

`"Fluorosulfuric"color(white)(mml)"FSO"_3"H"color(white)(mmmm)"-15.1"`
`"Carborane"color(white)(mmmm)"HCHB"_11"F"_11color(white)(mm)"-18.0"`
`"Magic"color(white)(mmmmmml)"FSO"_3"H·.SbF"_5color(white)(m)"-19.2"`
`"Fluoroantimonic"color(white)(m)"H"_2"F·SbF"_6color(white)(mmm)"-31.3"`

Thus, the most powerful acid is over `10^19` times as strong as 100 % sulfuric acid.