For the amino acid glycine (), the successive acid dissociation constants are analytically given as — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

The isoelectric point ($pI$) of a completely neutral amino acid is the pH at which it carries virtually no net electrical charge. This specific pH occurs precisely midway between the $pK_a$ values governing the protonation and deprotonation of the zwitterion. Thus, $pH (pI) = \frac{pK_{a1} + pK_{a2}}{2} = \frac{2.18 + 8.96}{2} = \frac{11.14}{2} = 5.57$.