Determine the buffer component concentration ratio (CB/WA) for a buffer with a pH of 4.7. K_a of boric acid (H₃BO₃) is 5.4 × 10⁻¹⁰.

• A. 4.568 : 1
• B. 2.706 × 10⁻⁵ : 1
• C. 1 : 4.568
• D. 1 : 2.706 × 10⁻⁵

Answer: (B)

Verified step by step guidance

1. Start by understanding the concept of a buffer solution, which consists of a weak acid and its conjugate base. The pH of the buffer is determined by the ratio of the concentrations of these components.
2. Use the Henderson-Hasselbalch equation to relate the pH of the buffer to the concentration ratio of the base and acid: \( \text{pH} = \text{pKa} + \log \left( \frac{[\text{Base}]}{[\text{Acid}]} \right) \).
3. Calculate the pKa of boric acid using its given Ka value: \( \text{pKa} = -\log(\text{Ka}) \). Substitute \( \text{Ka} = 5.4 \times 10^{-10} \) into the equation to find \( \text{pKa} \).
4. Substitute the given pH value (4.7) and the calculated pKa into the Henderson-Hasselbalch equation to solve for the concentration ratio \( \frac{[\text{Base}]}{[\text{Acid}]} \).
5. Rearrange the equation to isolate the concentration ratio: \( \frac{[\text{Base}]}{[\text{Acid}]} = 10^{\text{pH} - \text{pKa}} \). Calculate this expression to find the buffer component concentration ratio.