Resumen de Employing magnetic levitation to monitor reaction kinetics and measure activation energy
Lauren Benz, Karen E. Cesafsky, Tran Le, Aileen Park, David Malicky
This article describes a simple and inexpensive undergraduate-level kinetics experiment that uses magnetic levitation to monitor the progress and determine the activation energy of a condensation reaction on a polymeric solid support. The method employs a cuvette filled with a paramagnetic solution positioned between two strong magnets. The vertical position of the polymeric beads suspended in the paramagnetic solution correlates with the density of the beads and, consequently, with the progress of the chemical reaction within these beads. Varying the temperature of the reaction between the leucine-functionalized support and 2,5-diiodobenzoic acid under pseudo-first-order reaction conditions yields an activation energy of 65.4 ± 9.2 kJ/mol. This value compares well the activation energy of 63.5 ± 4.1 kJ/mol determined using a density analysis. This experiment combines a number of interdisciplinary concepts including organic chemistry, kinetics, and magnetism and, therefore, could be implemented in a number of undergraduate chemistry courses at various levels.
