The Kinetics of Dissolution Revisited

PAULA S. ANTONEL; PABLO A. HOIJEMBERG; LEANDRO M. MAIANTE; M. GABRIELA LAGORIO

JOURNAL OF CHEMICAL EDUCATION

Division of Chemical Education, Inc., American Chemical Society

Lugar: Winsconsin-Madison; Año: 2003 vol. 80 p. 1042 - 1043

0021-9584

The experiment presented here is an extension of a previously published article in this Journal: Dissolution Kinetics of Solids. Application with Spherical Candy (1). The extension was suggested by students in the physical chemistry laboratory course at the University of Buenos Aires?a good example of the creative participation of students in experimental practices. In the laboratory course a set of standard experiments are performed in the first part of the semester. In the last 20% of the course students choose the experiments. The students select material predominately from the Journal of Chemical Education under a flexible framework dictated by the course content and availability of instruments. In this exercise students are not passive receivers of knowledge and laboratory recipes but participate in the choice and design of their laboratory experiments. Autonomous thinking and manual abilities are improved from this exercise. After having chosen and performed the kinetics analysis on the dissolution of a spherical candy according to the procedure by Beauchamp (1), a group of students was interested in studying the dissolution behavior for another geometrical shape. A cylindrical candy was examined and the results are presented here. The experiment is simple, but the concepts involved (diffusion, Nernst layer, and kinetics) and the mathematical manipulation of data are very meaningful for students in a physical chemistry laboratory course.