Question

What is the $H^{+}$ ion concentration in ammonium acetate solution?
$(K_a=1.8\times {10}^{-5},K_b=1.8\times {10}^{-5},K_w=1.0\times {10}^{-14})$

Answer 1

Ammonium acetate is a salt of weak acid and weak base.

So $pH=7+\frac{1}{2}(p{K}_a-{pK}_b)$

$-\log \left[H^{+}\right]=7+\frac{1}{2}(-\log K_a+\log K_b)$

$-\log \left[H^{+}\right]=7+\frac{1}{2}\left(\log \frac{K_b}{K_a}\right)$

So $\left[H^{+}\right]={10}^{-7}$