A value that is often quite similar to the isoelectric point for a zwitterion is its isoionic point 26. This is the pH that arises when only the neutral form of zwitterionic compound (HA) is placed into a solution. The isoionic point of a zwitterion can be found by using the same equation we have already derived for a solution for an intermediate form of a polyprotic acid-base system, where we are now specifically looking at the Intermediate form HA.
A. Estimate the isoionic points for the following solutions:
1.5x10^-4 M valine
2.0x10^-5 M Glutamic Acid
5.5x10^-3 M Lysine
2.5x10^-4 M Histidine
B. Determine the isoelectric points for each of the above solutions.
C. How do the isoelectric points in Part B compare with isoionic points from Part A? Explain similarities or differences that you observe in these values.