Calculate the pH of a 5.7 M solution of aniline (C₆H₅NH₂;K_b = 3.8 $\times$ 10^-¹⁰): A)4.33 B)9.67 C)5.34 D)8.66 E)none of these

Question

Quizplus · Accepted Answer

Aniline is a weak base, so we need to use the Kb expression to calculate the concentration of hydroxide ions and then convert it to pH. 
First, calculate the concentration of hydroxide ions:
Kb = [NH2-][H2O]/[C6H5NH2]
3.8 × 10^-10 = [OH-]^2 / (5.7 M)
[OH-] = 8.05 × 10^-6 M 
Then, calculate the pH:
pH = 14 - pOH = 14 - (-log[OH-]) = 14 - (-log(8.05 × 10^-6)) = 9.67 
Therefore, the answer is B.

Calculate the PH of a 5 ×\times× 10-10): A)4

Calculate the PH of a 5 $\times$ 10^-¹⁰):
A)4