You have 75.0 mL of 0.11 M HA.After adding 30.0 mL of 0.10 M NaOH,the pH is 5.50.What is the K_a value of HA? A) 3.2 $\times$ 10^-6 B) 1.8 $\times$ 10^-6 C) 0.57 D) 1.1 $\times$ 10^-6 E) none of these

Question

Quizplus · Accepted Answer

The pH of 5.50 indicates that the solution is at the half-equivalence point, where [HA] = [A-]. At this point, pH = pKa. Therefore, pKa = 5.50, and Ka = 10^-5.50 = 3.16 x 10^-6, which is closest to option B.

You Have 75 ×\times× 10-6 B) 1 ×\times× 10-6 C) 0 ×\times× 10-6 E) None of These

You Have 75 $\times$ 10^-6
B) 1 $\times$ 10^-6
C) 0 $\times$ 10^-6
E) None of These