Consider the titration of 50.0 mL of 1.0 M glycine hy-drochloride [(H3NCH2COOH)CI], with 1.0 M NaOH. For +H3NCH2COOH, Ka for the carboxylic acid group is 4.3 X 10-3 and Kb, for the amino group is 6.0 X 10-5.
a. Calculate the pH after 25.0 mL, 50.0 mL, and 75.0 mL of NaOH has been added.
b. Sketch the titration curve and indicate the major amino acid species present after 0.0 mL, 25.0 mL, 50.0 mL, 75.0 mL, and 100.0 mL of 1.0 M NaOH have reacted completely. Assume the initial pH is 1.2 and the pH at the second equivalence point is 11.7.
c. At what pH do the majority of amino acid molecules have a net charge of zero? This pH is called the iso¬electric point.
d. At what pH is the net charge of the major amino acid species present equal to +1/2? -1/2?