Final answer:
The pH at the halfway point of an acid-base titration is equal to the pKa of the weak acid being titrated.
Step-by-step explanation:
The pH at the midpoint of the titration of a weak acid is equal to the pKa of the weak acid. This relationship holds true during acid-base titrations. In a titration, the pH starts changing as the strong base is added to the weak acid, and it reaches its halfway point at the equivalence point. At this point, the moles of weak acid and strong base are equal, resulting in equal concentrations of the weak acid and its conjugate base. Therefore, the pH equals the pKa at the halfway point of the titration.