In the titration of 100.0 mL of a 0.200 M solution of H₂A (K_a1 = 1.0 × 10^-5, K_a2 = 1.0 × 10^-8), what volume of 0.400 M NaOH must be added to reach a pH of 5.00? A) 25.0 mL B) 100.0 mL C) 0 mL D) 150.0 mL E) 50.0 mL

Question

Quizplus · Accepted Answer

At pH 5.00, the first dissociation of H2A is the dominant equilibrium. Using the Henderson-Hasselbalch equation for the first dissociation, the moles of NaOH needed to reach pH 5.00 can be calculated. The volume of 0.400 M NaOH required is 25.0 mL.

In the Titration of 100