Determine the pH of a 0.227 M C₅H₅N solution at 25°C.The K_b of C₅H₅N is 1.7 × 10^-9. A) 4.59 B) 9.41 C) 4.71 D) 10.14 E) 9.29

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Quizplus · Accepted Answer

To find the pH, first calculate the pOH using the formula: pOH = -log[OH⁻]. For C₅H₅N, use the Kb expression: Kb = [C₅H₅NH⁺][OH⁻]/[C₅H₅N]. Assume [OH⁻] = x, then Kb = x²/0.227. Solve for x: x = √(Kb × 0.227) = √(1.7 × 10⁻⁹ × 0.227) ≈ 6.2 × 10⁻⁶. Then, pOH = -log(6.2 × 10⁻⁶) ≈ 5.71. Finally, pH = 14 - pOH = 14 - 5.71 = 8.29. The closest option is 9.29.

Determine the PH of a 0