Question

if 0.420 m of a monoprotic weak acid is titrated with naoh, what is thr ph of the solution at the half-equivelance point

Answer 1

The pH of the solution at the half-equivalence point of a monoprotic weak acid titration is equal to the pKa of the weak acid.

Step-by-step explanation:

The pH of a solution at the half-equivalence point of a monoprotic weak acid titration can be calculated using the Henderson-Hasselbalch equation. At the half-equivalence point, the moles of weak acid left in the solution is equal to half of the initial moles of weak acid. This means that the ratio of the concentration of the weak acid to its conjugate base is 1:1.

Using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where pKa is the acid dissociation constant, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the weak acid.

Since the ratio of [A-] to [HA] is 1:1 at the half-equivalence point, we can assume that their concentrations are equal. Therefore, pH = pKa.