What is the pH of an aqueous solution that contains 0.39 M C₆H₅COOH and 0.14 M C₆H₅COONa?
K _a(C₆H₅COOH) = 6.3×10^{- 5}

Question

What is the pH of an aqueous solution that contains 0.39 M C₆H₅COOH and 0.14 M C₆H₅COONa? K _a(C₆H₅COOH) = 6.3×10^{- 5}

Quizplus · Accepted Answer

This is a buffer solution made of a weak acid (CH3COOH) and its conjugate base (CH3COONa). The pH of a buffer solution can be calculated using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the conjugate base and [HA] is the concentration of the acid. Given pKa = -log(6.3×10^-5) ≈ 4.20, [A-] = 0.14 M, and [HA] = 0.39 M, substituting these values gives pH ≈ 4.20 + log(0.14/0.39) ≈ 3.76.

What Is the PH of an Aqueous Solution That Contains