# What is the conjugate base of NH4+?

$N {H}_{3}$
$N {H}_{4}^{+} + {H}_{2} O \to N {H}_{3} + {H}_{3} {O}^{+}$
$N {H}_{4}^{+}$ is the acid because it donates an ${H}^{+}$ ion to the water. It then becomes ammonia ($N {H}_{3}$), which would be the conjugate base of $N {H}_{4}^{+}$.