A 50.00-mL solution of 0.10 M HNO₂ is titrated with a 0.10 M KOH solution. After 25.00 mL of the KOH solution is added, what is the pH in the titration flask? [K_a(HNO₂) = 4.5 × 10^-4]

Question

Quizplus · Accepted Answer

At the point where 25.00 mL of 0.10 M KOH has been added to 50.00 mL of 0.10 M HNO2, the reaction has reached the halfway point to the equivalence point because the volumes of acid and base are equal and their concentrations are the same. At this halfway point, the pH equals the pKa of the acid. The pKa can be calculated from the given Ka value for HNO2 (4.5 × 10^-4) as follows: pKa = -log(Ka) = -log(4.5 × 10^-4) ≈ 3.35.

A 5000-ML Solution of 0