Practical Adaptor for Heating Mantles The majority of the experiments performed in the organic chemistry laboratory oRen involve relatively long periods of heating, either in refluxing or distillations. Heating mantles have become an indispensable commodity whenever Bunsen burners have been eliminated from an experiment for safety reasons. Since most current undergraduate organic labs use both micro and macroscale experiments, the availability of different size heating mantles becomes necessary. Using a larger size mantle to heat a smaller round-bottom flask results in poor heat transfer to the flask and an eventual shorter lifetime of the mantle, due to the high temperature generated on the part of the surface that is not in contact with the flask. This becomes significantly important in an undergraduate organic lab where multiple units are needed. The use of sand or glass heads may provide a solution, but this can be messy in labs where large numhers . of students work. . . . . ...: We have found a way amund these problems by purehasing only 250-mL heating mantles with their corresponding powerstats and usiny them eff~cientlywith any smaller size round bottom flask via an adaptor device. Such a device, a s shown in the figure, is built of refractmy brick and is manufactured by a local artisan for less than $15 each. We have extensively used adaptors for 100- and 50-mL round bottom flasks, but there is, actually, no limitation for any other size or shape. The device has been used in our lab for over a year with excellent results.As expected from its design, the set-up requires a slightly longer time of induction a t the beginning (an estimated 6-8 min for a 100-mL round-bottom flask), but once hot, the set-up behaves like a regular heating mantle. The device offers great advantages (especially in the undergraduate lab): it is easier to clean spilled chemicals and can also be easily replaced. Moreover, it is safer because the surface of the round-bottom flask does not touch directly the surface of the mantle. Finally, it can be provided with a n extra hole to hold a thermometer if the monitoringthe temperature is required. We understand that commercially available heating mantles are rather inexpensive in the United States, but this device finds great application, especially among third world wuntries where the replacing of basic commodities, such a s heating mantles, on a routine basis is rather diff~cultor even impossible.
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whom any conespondenceshould be addressed
Gustavo Marln-Puga Universidad Catolica del Norte Antofagasta, Chile Paris Svoronos' Queensborough College of the City University of New York Bayside NY 11364
428
Journal of Chemical Education
