In a lactic acid solution at pH 4.8, the concentrations of lactic acid and lactate are 0.01 M and 0.087 M, respectively. The calculated pKa of lactic acid is ________.
In a lactic acid solution at pH 4.8, the concentrations of lactic acid and lactate are 0.01 M and 0.087 M, respectively. The calculated pKa of lactic acid is ________.
Answer
Answer: 3.9
Explanation:
Using the Henderson-Hasselbalch equation:
\text{pH} = \text{p}K_a + \log \left(\frac{[\text{A}^-]}{[\text{HA}]}\right)
\text{p}K_a = 4.8 - \log \left(\frac{0.087}{0.01}\right) = 4.8 - \log 8.7 \approx 4.8 - 0.94 = 3.9