Problem #16-4:
Given a 0.150 M solution of a triprotic aspartic acid, H$_3$Asp, with $K_{a1}$ = 1.02$\times$10$^{-2}$,
$K_{a2}$ = 1.26$\times$10$^{-4}$, and $K_{a3}$ = 9.95$\times$10$^{-11}$.
(a) What is the pH of this solution?
(b) Write the mass-balance expression for this solution of aspartic acid.
(c) Draw the ladder diagram and determine which species of this acid will dominate in the
solution at pH=2.50? pH=5.50?
(d) Write the fractional composition equations for all aspartic acid species.
Calculate the fractions, $\alpha_{H_3A}$, $\alpha_{H_2A^-}$, $\alpha_{HA^{2-}}$ , and $\alpha_{A^{3-}}$ , and also concentrations of all aspartic
acid species at pH=8.000. Based on your calculations, which of the aspartic acid species is
dominant in the solution at this pH?