# What are the acid base pairs in the following equation: HCOOH(aq) + H_2O(l) rightleftharpoons HCOO^(-)(aq) + H_3O^(+)(aq)?

$C {H}_{3} C O O H$ is a weak acid, with a conjugate base $C {H}_{3} C O {O}^{-}$.
${H}_{2} O$ is the base (in this case), and ${H}_{3} {O}^{+}$ is the conjugate acid.