Question

What is the pH of a buffer solution that is 0.211 M in hypochlorous acid (HClO) and 0.111 M in sodium hypochlorite? The Ka of hypochlorous acid is 3.8 ⋅ 10-8. What is the pH of a buffer solution that is 0.211 M in hypochlorous acid (HClO) and 0.111 M in sodium hypochlorite? The Ka of hypochlorous acid is 3.8 x 10-8.

a. 7.7

b. 0

c. 7.14

d. 14.28

e. 9.05

f. 6.86

Answer 1

c. 7.14

Step-by-step explanation:

The buffer solution is formed by a weak acid ( hypochlorous acid, HClO) and its conjugate base (hypochlorite ClO⁻, coming from sodium hypochlorite NaClO). We can calculate the pH using the Henderson-Hasselbach equation.

pH = pKa + log [base]/[acid]

pH = -log 3.8 × 10⁻⁸ + log 0.111/0.211

pH = 7.14