INVESTIGADORES
LAGORIO MarÍa Gabriela
artículos
Título:
The Kinetics of Dissolution Revisited
Autor/es:
PAULA S. ANTONEL, PABLO A. HOIJEMBERG, LEANDRO A. MAIANTE AND M. GABRIELA LAGORIO
Revista:
JOURNAL OF CHEMICAL EDUCATION
Editorial:
American Chemical Society
Referencias:
Lugar: Wisconsin; Año: 2003 vol. 80 p. 1042 - 1043
ISSN:
0021-9584
Resumen:
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
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.
At defined time intervals, the candy was taken out of
the solution, dried with an absorbing paper, weighed, and
its radius and thickness measured using a caliper. The temperature
was kept constant (25 C) during the experiment.