AssignmentNineKey - Take-Home Assignment#9 The ligand...

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Take-Home Assignment #9 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 species BH 2 + at more acidic pH levels, and may be deprotonated (at the OH) to form the anionic species B at more basic pH levels. The efficiency of extracting oxine from an aqueous phase into a organic phase, therefore, depends on pH. 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 an organic solvent BH (aq) ' BH (org) K D BH 2 + + H 2 O ' H 3 O + + BH K a1 BH + H 2 O ' H 3 O + + B - K a2 where K D is 720 when using CHCl 3 as the organic phase, 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
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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.

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AssignmentNineKey - Take-Home Assignment#9 The ligand...

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