AssignmentNine - This type of behavior is important in many...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Take-Home Assignment #9 Please turn in neatly worked solutions for the following problems. Feel free to work with one partner, in which case you may submit one set of solutions. Turn in your answers by Friday, April 8 th . The intention of this assignment is to consider the extraction of amphoteric compounds and the development of acid–base titration curves. 1. The ligand 8-hydroxyquinoline, C 9 H 6 (OH)N, also known as oxine, is amphoteric. If we represent its neutral form as BH, then oxine may be protonated (at the nitrogen) to form the cationic BH + at more acidic pH levels, and may be deprotonated (at the OH) to form the anionic B at more basic pH levels. The efficiency of extracting oxine from a polar aqueous phase into a non-polar organic phase, therefore, depends on pH.
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: This type of behavior is important in many systems, most notably for amino acids. The following equilibria are important in modeling the extraction efficiency for oxine between water and chloroform BH BH BH + + H + B-+ H + CHCl 3 H 2 O K D K a1 K a2 where K D is 720, and pK a1 and pK a2 are, respectively, 4.81 and 9.81. Derive a relationship between D and K D for this extraction. Assuming one extraction using 50.0 mL of 10.0mM oxine and 50.0 mL of CHCl 3 , calculate the extraction efficiency for oxine at pH levels of 1, 3, 5, 7, 9, 11, and 13. Graph your results (% extracted vs. pH) and identify the optimal pH for this extraction....
View Full Document

This note was uploaded on 04/02/2012 for the course CHEMISTRY 222 taught by Professor Mcdonald during the Fall '11 term at University of Illinois, Urbana Champaign.

Ask a homework question - tutors are online