# What is the conjugate base CH3COOH?

$C {H}_{3} C O {O}^{-}$
According to Lewis Concept 'a substance which donates ${H}^{+}$ to other is an Acid and a substance which accepts ${H}^{+}$ is a Base.
When $C {H}_{3} C O O H$ is dissolved in water it gives ${H}^{+}$ to water and become $C {H}_{3} C O {O}^{-}$.
$C {H}_{3} C O O H$ + ${H}_{2} O$ $r i g h t \le f t h a r p \infty n s$ $C {H}_{3} C O {O}^{-}$ +${H}_{3} {O}^{+}$
Now this $C {H}_{3} C O {O}^{-}$ is able to accept ${H}^{+}$ from ${H}_{3} {O}^{+}$.
So it is base. But actually this base ($C {H}_{3} C O {O}^{-}$) is derived from an acid $\left(C {H}_{3} C O O H\right)$ that' s why $C {H}_{3} C O {O}^{-}$ is conjugate base of $\left(C {H}_{3} C O O H\right)$ acid.