Chapter 17, Problem 8E

What concentration of ammonia. $\left[{\text{NH}}_{\text{2}}\right]$ , should be present r a solution with $\left[{\text{NH}}_{\text{2}}^{\text{4}}\right]=0.732$ M to produce a buffer solution with ph = 9.12? For ${\text{NH}}_{\text{3}}{\text{,K}}_{\text{b}}\text{=1}{\text{.8×10}}^{\text{-5}}$ .