# How would you use the Henderson-Hasselbalch equation to calculate the pH of a solution that is 0.17 M in HCHO_2 and 0.10 M in NaCHO2?

Dec 3, 2015

$p H = 3.51$

#### Explanation:

In order to use the Henderson-Hasselbalch equation, you will need the acid dissociation constant ${K}_{a}$ of formic acid, which is ${K}_{a} = 1.8 \times {10}^{- 4}$.

Therefore, Henderson-Hasselbalch equation is written as:

$p H = p {K}_{a} + \log \left(\frac{\left[N a C H {O}_{2}\right]}{\left[H C H {O}_{2}\right]}\right)$

$\implies p H = 3.74 + \log \left(\frac{0.10 \cancel{M}}{0.17 \cancel{M}}\right)$

$\implies p H = 3.51$

Here is a video that explains buffer solution and the Henderson-Hasselbalch equation and it is origin and use.
Acid - Base Equilibria | Buffer Solution.