Chemical Education Today
Letters Potential Hazard
The authors reply:
Use of the apparatus for fractional distillation shown in Figure 4 of the article “Learning in Chemistry with Virtual Laboratories” (1, p 349) would be very likely to cause an explosion because the apparatus shown has no vent. Also, in my experience, ring stands (or racks) and clamps should be included in apparatus diagrams if students are to learn to assemble safe, sturdy setups. Being vertical is a very important factor in the performance of fractionating columns, and a plumb line should be used in setting up a column. In a column that is not perfectly vertical, the liquid that condenses simply runs down the low side instead of being redistilled repeatedly.
We don’t understand the problem Umland describes. The system described is not closed, although the published diagram may appear to be closed. The system works under atmospheric pressure, so an explosion is unlikely to happen.
Literature Cited 1. Martínez-Jiménez, P.; Pones-Pedrajas, A.; Climent-Bellido, M. S.; Polo, J. J. Chem. Educ. 2003, 80, 346–352.
Pilar Martínez Jiménez Department of Applied Physics, Ed. C-2 Campus of Rabanales 14071 Córdoba, Spain
[email protected] Maria Salud Climent Bellido Department of Organic Chemistry, Ed. C-3 Campus of Rabanales 14071 Córdoba, Spain
[email protected] Jean B. Umland 21 South End Avenue, #423 New York, NY 10280-1063
www.JCE.DivCHED.org
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Vol. 81 No. 5 May 2004
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Journal of Chemical Education
641
