Question

The pKa of acetic acid is approximately 4.76. What is the pH of a 0.05 M acetic acid solution in water? Choose the answer closest to the one you calculate.

Answer 1

3.46

Step-by-step explanation:

Hello,

This question can be solved using Henderson-Hasselbalch equation.

The dissociation equation of acetic acid in water is

CH₃COOH + H₂O ⇄ CH₃COO⁻ + H₃O⁺

pH = pKa + log([conjugate base] / [weak acid])

Conjugate base = acetic acid

Weak acid = water

pKa = 4.76

pH = 4.76 + log([0.05]/[1])

pH = 4.76 + log(0.05)

pH = 4.76 + (-1.30)

pH = 3.46

From the above solution, the pH of the solution is 3.46