# What is the most powerful acid in the world?

Apr 10, 2018

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 $\text{p} {K}_{\textrm{a}}$ values to measure their acidities.

Instead, we must use Hammett ${H}_{0}$ values.

${H}_{0}$ is similar to $\text{p} {K}_{\textrm{a}}$ in that it is a logarithmic scale and a more negative value means a stronger acid.

Here is a table of some superacids.

$\underline{\boldsymbol{\text{Acid"color(white)(mmmmmm)"Structure} \textcolor{w h i t e}{m m l} {H}_{0} \textcolor{w h i t e}{m}}}$
$\left(\text{Sulfuric"color(white)(mmmmm)"H"_2"SO"_4color(white)(mmmml)"-12.0}\right)$
$\text{Chlorosulfuric"color(white)(mml)"ClSO"_3"H"color(white)(mmmll)"-12.8}$
$\text{Triflic"color(white)(mmmmmml)"CF"_3"SO"_3"H"color(white)(mmll)"-14.1}$
$\text{Oleum"color(white)(mmmmmm)"H"_2"O"_4"·SO"_3color(white)(mmll)"-15}$

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

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