suppose you perform a titration of a monoprotic weak acid and you determine the ph at the equivalence point is 9.21 and the ph at the half-equivalence point is 4.24. what is the pka of the acid? enter your answer numerically.

Respuesta :

The pKa of the weak acid, based on the titration results, is 4.24.

Only the half-equivalence pH is needed to answer this.

At the half-equivalence point of the titration, half of the monoprotic acid HA has been neutralized and converted to the appropriate salt. That means that the concentration of the acid [HA] is equal to the concentration of its anion [A⁻]. Now, we can consult the Henderson-Hasselbalch equation:

[tex]pH = pKa + log\frac{[A^{-} ]}{[HA]}[/tex]

Because [A⁻] = [HA], that means that:

[A⁻]/[HA] = 1

log(1) = 0

pH = pKa

So, at the half-equivalence point in the titration of the weak acid the pH value of the solution is equal to the pKa value of the weak acid, so pKa = 4.24

You can learn more about weak acids here:

brainly.com/question/12811944

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