The amino acid L-histidine has three acid-base equilibria, with pKa values of 1.78, 5.97, and 8.97.
(a) Plot the fraction of solute species present in solution in the pH range 0 to 14.
Use the graph to determine
(b) The major species present in solution at pH = 7.5.
(c) The pH value at which equal amounts of the singly and doubly deprotonated forms are present.
(d) The pH necessary to achieve greater than 99% fully deprotonated histidine.
(e) The pH range for which three different deprotonated forms are present in significant quantities.