Bismuth Crystals: Preparation and Measurement of Thermal and Electrical Properties
- Autores: Gianna Aleman Milan, Brian Millier, Andrew Ritchie, Craig Bryan, Sarah Vinette, Bjorn Wielens, Mary Anne White
- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 90, Nº 12, 2013, págs. 1675-1680
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
-
Resumen
We describe a laboratory experiment that serves as an introduction to solid-state and materials science, a topic that requires additional attention in the undergraduate chemistry laboratory curriculum. The experiment illustrates the long-range translational order, crystal growth, and the macroscopic manifestations of that order. This is demonstrated through the preparation and characterization of large, well-formed bismuth crystals, an aesthetically pleasing product. The characterization of the grown bismuth crystals involves determination of melting point and enthalpy of fusion via differential scanning calorimetry. The temperature dependence of the electrical resistance of grown bismuth crystals is also measured. Students are encouraged to consider the effect of metallic bonding interactions on the melting of the crystal samples and on their ability to conduct electricity. Students also analyze how the impurities influence the melting point and the electrical properties. The experiment is suitable for use in the third- or fourth-year undergraduate laboratory and is performed by students in one four-hour session. The experiment could be adapted to two laboratory sessions, with the first two-hour session covering crystal growth, and the second two-hour session focused on thermal and electrical characterization.
