We’re being asked to **calculate the pH of a solution that contains formic acid (HCHO _{2}) and sodium formate (NaCHO_{2})**.

A solution that contains a **weak acid** and its **conjugate base** is a **buffer solution**.

The pH of a buffer solution can be determined using the **Henderson-Hasselbalch equation**.

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

Solve an equilibrium problem (using an ICE table) to calculate the pH of of each solution:

a solution that is 0.18 *M* in HCHO_{2} and 0.13 *M* in NaCHO_{2}