Question

Which is a stronger acid, sulfurous acid or sulfuric acid? Why?

Short answer

${\mathrm{S}\mathrm{O}}_4^{-}$ is the stronger acid because of stability${\mathrm{S}\mathrm{O}}_4^{-}$of ion.

Step-by-step solution

To find the stronger acid.

${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$is much stronger acid then the${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_3$because there is an extra double bonded oxygen atom on the sulfur atom in sulfuric acid.

The unprotonated $O$helps with delocalization of electron in deprotonated ion making the$S{O}_4^{2-}$ion more stable than the$S{O}_3^{2-}$ion.