Final answer:
If glycine (COOH, pKa = 2.3, NH₂ pKa = 9.6) is in a solution of pH 2.3, it exists at a pH equal to its COOH pKa value.
Step-by-step explanation:
At pH 2.3, glycine's carboxyl group is in equilibrium between protonated and deprotonated forms, while the amino group remains fully protonated as the ammonium ion. At this pH, the carboxyl group of glycine will be in equilibrium, with half of the molecules in the protonated form (COOH) and half in the deprotonated carboxylate form (COO⁻). However, since the pH is much lower than the pKa of the amino group, the amino group (NH₂) will be fully protonated and exist as the ammonium ion (NH₃⁺).