# What is the conjugate base of HCO_3^-?

$H C {O}_{3}^{-} + {H}^{+} \rightarrow {H}_{2} C {O}_{3} \left(a q\right)$
$\text{Carbonic acid,}$ ${H}_{2} C {O}_{3}$. As far as anyone knows, $\text{carbonic acid}$ is hydrated, i.e. dissolved, carbon dioxide, i.e. ${H}_{2} O \cdot C {O}_{2}$.