Which indicator is most appropriate for the titration of acetic acid with NaOH? The K_a for CH₃CO₂H is 1.8 × 10−⁵.

Question

Quizplus · Accepted Answer

Acetic acid is a weak acid with a pKa of 4.75, which means that at pH values below 4.75, most of the acetic acid exists in the undissociated form. Therefore, to determine the endpoint of the titration accurately, an indicator with a pKa value close to 4.75 is needed. While methyl red and bromthymol blue have pKa values of 5.1 and 6.0, respectively, phenolphthalein has a pKa of 9.4, making it the most suitable indicator for the titration of acetic acid with NaOH.

Which Indicator Is Most Appropriate for the Titration of Acetic