(a) What is the pH of 50 mL of a 0.2M glycolic acid aqueous solution after adding 5 mL of 0.25 M KOH? The pKa of glycolic acis is 3.83 at 25 ∘C.

Hg = glycolic acid

Hg = 0.2M x 50 mL = 10 mmols.
KOH = 5mL x 0.25M = 1.25 mmols.
.......Hg + OH^- ==> g^- H2O
I......10...0........0....0
added......1.25............
C...-1.25.-1.25.....1.25
E.....8.75..0.......1.25..1.25

Use the Henderson-Hasselbalch equation, substitute and solve for pH.