Final answer:
The pKa values of functional groups on a titration curve correspond to the pH values at which the weak acid is half dissociated.
Step-by-step explanation:
The pKa values of each functional group observed on the titration curve are determined by the acid-base equilibrium of the weak acid. The pKa is a measure of the acidity of a compound and is related to the concentration of H+ ions in solution. In the titration curve, when the pH is equal to the pKa, the weak acid is half dissociated and half undissociated.
For example, if a weak acid has a pKa value of 4, at pH 4, the weak acid is 50% dissociated and 50% undissociated. As the pH increases above the pKa, the weak acid becomes more dissociated, and as the pH decreases below the pKa, the weak acid becomes more undissociated.
Therefore, to determine the pKa values of each functional group observed on the titration curve, you need to identify the pH values at which the weak acid is half dissociated. These pH values correspond to the pKa values of the functional groups.