Question

Why is sulfuric acid considered a Bronsted acid?

Answer 1

Because it is a proton donor in aqueous solution.

Explanation:

The first protonation:

`H_2SO_4(aq) + H_2O(l) rarr HSO_4^(-) + H_3O^+`

This reaction goes to completion in water.

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

`HSO_4^(-) + H_2O rarr SO_4^(2-) + H_3O^+`

Overall, `H_2SO_4(aq) + 2H_2O(l) rarr 2H_3O^(+) + SO_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 `"Bronsted"`, and `"Brønsted"`. Given that he knew that I am a very poor linguist, he just laughed and said not to bother.