Answer
$H_3O^+$ and $H_2O$ are a conjugate acid-base pair.
Work Step by Step
- Fast method:
A conjugate acid-base pair has exactly one $H^+$ as a difference. So, this is a valid pair.
- Other method:
1. Identify the base:
- $H_2O$
** $H_2O$ is amphiprotic, but it is the only one of those 2 that can act as a base.
2. Add a $H^+$ to it:
- $H_3O^+$
Compare with the other substance:
$H_3O^+ = H_3O^+$
- So, this is a conjugate acid-base pair.
