Question

What is the conjugate acid of HPO4^2-?

Answer 1

The conjugate acid of any species, is that species plus a proton; so it's `H_2PO_4^(-)`.

Explanation:

When we add a proton, we must conserve both mass and charge, we add `H^+` to `HPO_4^(2-)` so the conjugate acid is simply `H_2PO_4^(-)`. What is the conjugate acid of `H_2PO_4^(-)`?

See also [here.](https://socratic.org/questions/what-is-the-conjugate-acid-of-nh3-1)