Question

pH of 0.05 M (CH₃COO)₂Ca (pK_a = 4.74) is –

• A. 8.72
• B. 8.87
• C. 7
• D. 1.30

Answer 1

Answer: (B)

8.87

Answer 2

[CH₃COO^–] = 2 × 0.05 = 0.1

pH = $\frac{1}{2}$ [pK_w + pK_a + log C]

= $\frac{1}{2}$ [14 + 4.74 + log 0.1]

= $\frac{1}{2}$ [14 + 4.74 – 1] = 8.87