A buffer solution is prepared in which the concentration of NH_3 is 0.30 M and the concentration of NH_4^+ is 0.20 M. If the equilibrium constant,…

A buffer solution is prepared in which the concentration of $\displaystyle \mathrm{NH}_3$ is $\displaystyle 0.30$ M and the concentration of $\displaystyle \mathrm{NH}_4{ }^{+}$ is $\displaystyle 0.20$ M. If the equilibrium constant, $\displaystyle K_{\mathrm{b}}$ for $\displaystyle \mathrm{NH}_3$ equals $\displaystyle 1.8 \times 10^{-5}$, what is the pH of this solution ? $\displaystyle (\log 2.7=0.43)$