Question

The $p{K}_a$ of acetic acid and $p{K}_b$ of $N{H}_{4}OH$ are 4.75 and 4.75 respectively. Find the pH of ammonium acetate solution?

Answer 1

Answer: 7

Ammonium acetate is a salt of weak acid and weak base.
So pH is given as
$pH=\frac{1}{2}\left(p{K}_w+p{K}_a-p{K}_b\right)$
$=\frac{1}{2}\left(14+4.75-4.75\right)$
$=7$