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  Home > JCE Print > Journal of Chemical Education > Issues > 2000  > September  >
In the Laboratory
Acid-Base Titration of (S)-Aspartic Acid: A Circular Dichroism Spectrophotometry Experiment
Ana M. V. Cavaleiro and Júlio D. Pedrosa de Jesus
Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
Cover
September 2000
Vol. 77 No. 9
p. 1218
Abstract
The magnitude of the circular dichroism of (S)-aspartic acid in aqueous solutions at a fixed wavelength varies with the addition of strong base. This laboratory experiment consists of the circular dichroism spectrophotometric acid-base titration of (S)-aspartic acid in dilute aqueous solutions, and the use of the resulting data to determine the ionization constant of the protonated amino group. The work familiarizes students with circular dichroism and illustrates the possibility of performing titrations using a less usual instrumental method of following the course of a reaction. It shows the use of a chiroptical property in the determination of the concentration in solution of an optically active molecule, and exemplifies the use of a spectrophotometric titration in the determination of an ionization constant.
Supplement
Student material and instructor notes are available.
*  Contents JCE2000p1218W.doc (Microsoft Word); JCE2000p1218Wfig4.xls (Microsoft Excel); JCE2000p1218Wfig5.xls (Microsoft Excel)
*  Download
JCE2000p1218W.pdf

JCE2000p1218W.zip

JCE2000p1218W.sit
More Information
*  Citation
 Cavaleiro, Ana M. V.; de Jesus, Júlio D. Pedrosa. J. Chem. Educ. 2000 77 1218.
*  Keywords
 Acid-Base Chemistry; Amino Acids; Instrumental Methods; Laboratory Instruction
*  History
 Created:
Last Updated:		 August 29, 2000
August 31, 2005
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