We’re being asked to calculate the pH of a solution that is 0.111 M CH_{3}COOH and 0.558 M CH_{3}COONa.

In this case, we will be using the Henderson-Hasselbalch equation which can be used for buffer solutions

Recall the Henderson-Hasselbalch equation:

$\overline{){\mathbf{pH}}{\mathbf{=}}{{\mathbf{pK}}}_{{\mathbf{a}}}{\mathbf{+}}{\mathbf{log}}\left(\frac{\mathbf{conjugate}\mathbf{}\mathbf{base}}{\mathbf{weak}\mathbf{}\mathbf{acid}}\right)}$

Calculate the pH of a solution that is 0.111 M CH_{3}COOH and 0.558 M CH_{3}COONa. K_{a} of CH_{3}COOH is 1.8 x 10^{-5}.

a. 5.45

b. 5.02

c. 5.67

d. 6.91

e. 6.82