Microscale Demonstration of Charge Modification upon Complexation by Ion Exchange

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 5 Issue 2 (2000) pp 61-63

Microscale Demonstration of Charge Modification upon Complexation by Ion Exchange

Jorge G. Ibanez,* and Allan Fis

Depto. de Ciencias, Universidad Iberoamericana, Prol. Reforma #880, 01210 México D.F., México

Published online: 2 April 2000

Abstract. A small plastic syringe (or a Pasteur pipet) is used as an ion-exchange microcolumn model to demonstrate the principles of ion exchange and charge modification upon complexation. In the first part of the experiment, the removal of cobalt ions (cations) from aqueous solution is visually demonstrated. Then, Co2+ is reacted with the negatively charged EDTA (ethylenediaminetetraacetate) ion to form a complex anion. When passed through a cation exchange column, the Co2+ ions are completely retained whereas the complexed cobalt ions are not removed at all. This experiment is appropriate for a first- year chemistry laboratory, and takes approximately one hour to complete.

Key Words: Laboratories and Demonstrations; general chemistry, ion exchange, microscale

(*) Corresponding author. (E-mail: jorge.ibanez@uia.mx )

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