A Calorimeter for General Chemistry Many laboratory manuals in general chemistry include a calorimetry experiment to coordinate with introducbory discussions of thermochemistry. A major difficulty for such an experiment is designing a convenient, inexpensive calori&eter that can still give reasonably accurate results. In pursuit of this objective, the use of foam plastic or polystyrene cupsL and glassware covered with asbestos paper2 has been suggested. A suitable calorimeter is now available which has all of the desired qualities listed above as well as being CALORWETER virtually unbreak-
able. I t is marketed under the disguise "Insulated Food Jar" and consists of a 5 1/2-07, insulated polyethylene screw cap jar (see illu~tration.~)By drilling a 5/64-in. hole in the lid, a standard thermometer can be inserted and will fit snugly preventing heat leakage. If these calorimeters are checked out from the stockroom prior to use only a small inventory is needed (we keep 48 for use by more than 400 students). We have not found it necessary to include a stirrer since slight swirling produces adequate mixing. These "calorimeters" can also be used as miniature cold traps being unaffected by Dry Ice-acetone slurries. 'FRANTZ, H. W., A N D MALM,L. E., "Chemical Principles in the Laboratory," W. H. Freeman and Co., San Francisco, 1966, p. 131. HUTTON,W., "General Chemistry Laboratory Text," Charles E. Merrill Books, Inc., Colnrnbus, Ohio, 1965, p. 77. BEESCIA,F., ARENTS,J., MEISLICH,R.,AND TURK,A,, "Fundamentals of Chemistry, Laboratory Studies," Academic Press, New York, 1966, p. 151. T h i s jar k manufactured by Bee Plastic?, Inc., Waltham, Mass., and costs less than 81.00. Similar jars are probably avsilsble in retail stores.
D. L. GARIN UNIVERSITY OF MISSOURI AT ST. LOULS ST. LOUIS,A ~ ~ S O U R63121 I
Volume 45, Number 1 , Jonvory 1968
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