Why is sulfuric acid considered a Bronsted acid?
Because it is a proton donor in aqueous solution.
The first protonation:
This reaction goes to completion in water.
However, the conjugate base of sulfuric acid, bisulfate anion, is itself a reasonably strong Bronsted acid:
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