Resumen de Using Beads and Divided Containers To Study Kinetic and Equilibrium Isotope Effects in the Laboratory and in the Classroom
Dean J. Campbell, Emily R. Brewer, Keri A. Martinez, Tamara J. Fitzjarrald
The purpose of this laboratory experiment is to study fundamental concepts of kinetics and equilibria and the isotope effects associated with both of these concepts. The concepts of isotopes in introductory and general chemistry courses are typically used within the contexts of atomic weights and radioactivity. Kinetic and equilibrium isotope effects are typically covered in upper-level courses in the chemistry curriculum, but the concepts behind these isotope effects are also relevant to introductory chemistry. Beads (specifically “airsoft” pellets) of the same size but with two different masses can be used to represent isotopes of two different masses in classroom activities. Plastic Petri dishes with dividers can be modified so that the chambers can represent different states of matter or different chemical species. When the Petri dishes containing a number of beads of each mass are shaken, the beads will be distributed among the chambers in a manner similar to isotope distributions in matter. The bead/Petri dish shakers have been used as a chemistry demonstration and as a chemistry laboratory activity. Additionally, LEGO-based models containing chambers separated by dividers can be used to demonstrate the phenomena of kinetics and equilibria. The laboratory experiments can be performed in one laboratory period and are designed to touch on a variety of topics relevant for general chemistry students, although the lab could also be easily used for students with more or less advanced backgrounds.
