# Why is sulfuric acid considered a Bronsted acid?

Mar 28, 2016

Because it is a proton donor in aqueous solution.

#### Explanation:

The first protonation:

${H}_{2} S {O}_{4} \left(a q\right) + {H}_{2} O \left(l\right) \rightarrow H S {O}_{4}^{-} + {H}_{3} {O}^{+}$

This reaction goes to completion in water.

However, the conjugate base of sulfuric acid, bisulfate anion, is itself a reasonably strong Bronsted acid:

$H S {O}_{4}^{-} + {H}_{2} O \rightarrow S {O}_{4}^{2 -} + {H}_{3} {O}^{+}$

Overall, ${H}_{2} S {O}_{4} \left(a q\right) + 2 {H}_{2} O \left(l\right) \rightarrow 2 {H}_{3} {O}^{+} + S {O}_{4}^{2 -}$

As in any chemical reaction, both MASS and CHARGE are conserved.

PS I once asked a Scandinavian, who was an excellent linguist, what was the difference in pronunciation between $\text{Bronsted}$, and $\text{Brønsted}$. Given that he knew that I am a very poor linguist, he just laughed and said not to bother.