A food chemist studying the formation of lactic acid in sour milk prepares a buffer that is 0.58 M in lactic acid (HC3H5O3) and 0.36 M in sodium lactate (NaC3H5O3). Use the Henderson–Hasselbalch equation to calculate the pH of the buffer solution.

Verified step by step guidance

1. Identify the components of the buffer solution: lactic acid (HC3H5O3) as the weak acid and sodium lactate (NaC3H5O3) as the conjugate base.
2. Write the Henderson–Hasselbalch equation: \( \text{pH} = \text{pK}_a + \log \left( \frac{[\text{A}^-]}{[\text{HA}]} \right) \), where \([\text{A}^-]\) is the concentration of the conjugate base and \([\text{HA}]\) is the concentration of the weak acid.
3. Look up or calculate the \(\text{pK}_a\) of lactic acid. The \(\text{pK}_a\) is the negative logarithm of the acid dissociation constant \(K_a\).
4. Substitute the given concentrations into the Henderson–Hasselbalch equation: \([\text{A}^-] = 0.36\, \text{M}\) and \([\text{HA}] = 0.58\, \text{M}\).
5. Calculate the pH by solving the Henderson–Hasselbalch equation with the substituted values.