The K_a of phenol is 1.3 * 10^-10.For a solution labeled "1.0 *10^-3 M aqueous phenol," A)K_w/[H₃O⁺] [phenol]_initial. B)K_w/[H₃O⁺]

Question

The K_a of phenol is 1.3 * 10^-10.For a solution labeled "1.0 *10^-3 M aqueous phenol," A)K_w/[H₃O⁺] >> [phenol]_initial. B)K_w/[H₃O⁺] << [phenol]_initial. C)[H₃O⁺] > 10^-6. D)pH ~ 4. E)[H₃O⁺] = [H₃O⁺]²/[phenol]_initial.

Quizplus · Accepted Answer

The expression given in the first part of the question is the acid dissociation constant (Ka) of phenol. The solution given in the question has a known concentration of phenol, and we can use the Ka value to calculate the concentration of H+ ions in the solution. From the pH calculation, it can be determined that the pH of the solution is around 4. 
Option A is incorrect as it implies that the concentration of phenol is greater than the concentration of the buffer components, which isn't necessarily true.
Option C is incorrect as the expression given in the question tells us that the buffer is indeed capable of maintaining a pH of around 4, so the concentration of the buffer components doesn't need to be greater than 10 times the concentration of phenol.
Option D is partially correct, but it doesn't answer the question asked.
Option E is incorrect as it gives an incorrect expression for the calculation.

The Ka of Phenol Is 1

The K_a of Phenol Is 1