Question

What is the conjugate acid of HPO2^2-?

Answer 1

`"H"_2"PO"_2^-`

Explanation:

If we can find the conjugate acid of `"HPO"_2^(2-)`, then `"HPO"_2^(2-)` itself is a base.

Since it has a negative charge, it must lack a positive charge, i.e. it lacks a proton. Therefore, it wants to act as a Bronsted base.

If the molecule is a Bronsted base, then it can accept a proton `("H"^+)`.

Thus, if we add a hydrogen ion (a proton) to the ion, we get `"H"_2"PO"_2^-`.