A weak acid is titrated with a strong base and the pH is measured at each...

A weak acid is titrated with a strong base and the pH is measured at each interval. It the equivalence point is reached when 30 mL of the base has been added, describe how the pKa of the acid can be determined.

Expert Solution

The method is described for any general monoprotic acid HA
dissociation of weak acid ---
HA H⁺ + A^-
dissociation constant of HA , Ka = [H⁺][A^-]/[HA]
when concentrations of both HA and A^- are equal then Ka = [H⁺]
this is also revealed by the henderson equation.
so pH = pKa when weak acid and it's conjugate base concetrations are same.This occurs at half equivalence point. For the given problem half equivalence volume of NaOH is 15 ml. so the pH value corresponding to 15 ml is noted from the plot , Which is pKa value of the given weak acid.
Multi protic acids dissociations also can be studied by the same method.

queen_honey_blossom answered 2 years ago

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