The amino acid glycine is often used as the main ingredient of a buffer in biochemical experiments. The amino group of glycine, which has a pKa of 9.6, can exist either in the protonated form (-NH3+) or as the free base (-NH2), because of the reversible equilibrium.

(a) In what pH range can glycine be used as an effective buffer due to it's amino group?

(b) In a 0.1 M solution of glycine at pH 9.0, what fraction of glycine has it's amino group in the -NH3+ form?

(c) How much 5 M KOH must be added to 1.0 L of 0.1 M glycine at pH 9.0 to bring it's pH to exactly 10.0?

(d) When 99% of the glycine is in it's -NH3+ form, what is the numerical relation between the pH of the solution and the pKa of the amino group?