Chemistry - Ionic Equilibrium Question with Solution | TestHub

$\begin{array}{ccccccc}{\text{CH}}_{\text{3}}\text{COOH}\text{(aq)}& \text{+}& {\text{NH}}_{\text{3}}\text{(aq)}& \to & {\text{CH}}_{\text{3}}{\text{COONH}}_{\text{4}}\text{(aq)}& & \\ \text{1}\text{m}\text{mol}& & \text{1}\text{m}\text{mol}& & \text{1}\text{m}\text{mol}& & \\ & & & & & & \end{array}$
$\left[{\text{CH}}_{\text{3}}{\text{COONH}}_{\text{4}}\right]\text{=}\frac{\text{1}\text{mM}}{\text{20}\text{mL}}\text{=}\text{0}\text{.05 M}$
Salt of weak Acid + weak base.
$\text{pH}=\frac{1}{2}\left(\text{p}{\text{K}}_{\text{w}}+\text{p}{\text{K}}_{\text{a}}-\text{p}{\text{K}}_{\text{b}}\right)$
$=\frac{1}{2}\left(14+5-5\right)=7$