# Which is the stronger acid in each of the following pair H_2SeO_3 or H_2SeO_4?

Jul 31, 2015

${\text{H"_2"SeO}}_{4}$ is the stronger acid.

#### Explanation:

For oxyacids with the same central atom, the acidity increases as the number of atoms bonded to the central atom increases.

Thus, we predict that ${\text{H"_2"SeO}}_{4}$ should be a stronger acid than ${\text{H"_2"SeO}}_{3}$.

This is confirmed by their ${K}_{\text{a}}$ values .

${\text{H"_2"SeO}}_{4}$ has ${K}_{a} > 1$, while ${\text{H"_2"SeO}}_{3}$ has K_a = 2.3 × 10^-3.