When an acid, HA, is titrated with 0.1 M NaOH, the pH at the half equivalence point of the titration is 4.5. What is the K_a of the acid?

Question

Quizplus · Accepted Answer

At the half equivalence point of a titration of a weak acid with a strong base, the pH equals the pKa of the acid. The pKa can be calculated using the formula pH = pKa when half of the acid has been neutralized. Given that the pH at the half equivalence point is 4.5, the pKa of the acid is also 4.5. The Ka (acid dissociation constant) can be found by taking the inverse log of -pKa: Ka = 10^-pKa = 10^-4.5 = 3.2 x 10^-5.

When an Acid, HA, Is Titrated with 0