CHM 2354 Lecture Notes - Lecture 9: Isoelectric Point, Zwitterion, Acid Dissociation Constant

• School: University of Ottawa
• Department: Chemistry
• Course: CHM 2354
• Professor: Maxim Berezovski

Document Summary

Chm 2354 lecture 9 polyprotic systems. Polyprotic systems: acids or bases that can donate or accept more than one protin h+ Includes proteins, which is why the activity of proteins are ph dependant: some amino acids have acidic or basic substituents. Amino acids: called a zwitterion molecule with both positive and negative charge, at low ph, both ammonium and carboxy group protonated, at high ph neither group is protonated, stabilized by interaction with the solvent. There are three components to the process (3 forms) H2l+ is a weak acid and hl very weak acid. Can assume it behaves as monoprotic is valid ka = ka1 are is a a. Triprotic system leave off on slide 26. Equlibria for triprotic systems: h3a is treated as a monoprotic acid, This depends on the ph of the sample and the pka values. At pka, 1:1 mixture of ha and a- For monoprotic, a- is predominant when ph > pka.