## Chemistry: The Molecular Science (5th Edition)

$O^{2-}$ and $H_3O^+$ aren't a conjugate acid-base pair.
- Fast method: A conjugate acid-base pair has exactly one $H^+$ as a difference. So, this isn't a valid pair. - Other method: 1. Identify the base: - $O^{2-}$ 2. Add a $H^+$ to it: - $OH^-$ Compare it to the other substance: $OH^- \ne H_3O^+$ - So, this isn't a conjugate acid-base pair.