To a 25.00 mL volumetric flask, a lab technician adds a 0.400 g sample of a weak monoprotic acid, HA, and dilutes to the mark
with distilled water. The technician then titrates this weak acid solution with 0.0894 M KOH. She reaches the endpoint after
adding 48.97 mL of the KOH solution.
After the technician adds 15.51 mL of the KOH solution, the pH of the mixture is 5.11. Determine the pK, of the weak acid