A Device To Emulate Diffusion and Thermal Conductivity Using Water Flow
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Harvey F. Blanck [1]
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[1] Austin Peay State University
Austin Peay State University
Estados Unidos
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- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 82, Nº 10, 2005, pág. 1523
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
Time places severe limitations on which experiments can be demonstrated in the classroom. Since diffusion in liquids is a slow process, most classroom demonstrations of diffusion involve gaseous diffusion. They do not show quantitatively the relative concentrations of the diffusing substances nor do they demonstrate the various different general methods of determining diffusion coefficients. An acrylic plastic device has been designed using water flowing through a series of cells to visually emulate diffusion and thermal conductivity. Water height emulates concentration or temperature. It can emulate a steady-state condition in which there is a constant gradient of concentration or temperature change with distance as well as the approach to this steady state. It can emulate experiments in which mass diffuses across a boundary showing the resulting 1 - error function curve. It can emulate diffusion from a plane (point) source forming a Gaussian curve. Results are obtained in a matter of a few minutes. The lightweight, rugged plastic model is easy to transport, easy to use, easy to store, has no moving parts, and requires only water to operate. This mechanical device should be quite helpful in both classroom and laboratory discussions of diffusion and thermal conductivity.
