BURNING WITHOUT ACCESS TO AIR Submitted by: Voldemar Alfthaii, Helsinki, Finland Checked by: Dale Dreisbach, Hiram College, Hiram, Ohio
PREPARATION
Provide a six-inch Pyrex test mounted on a ring stand and clamped a t an angle of GOo; a 400 ml beaker beaker; concenhalf filled with water at 500 C; a 50 trated sulfuric acid and ethanol. DEMONSTRATION
Weigh - about 0.1 e of watch glass. By means of a small funnel introduce concentrated sulfuric acid to a height of 3 em in the test tube. Pour pure alcohol slowly along the wall of the test tube to form a layer of about 6 em. Carefully move the test tube into a vertical position avoiding any mixing of the two layers. Drop a few crystals of KMn04 into the tube, cover
with the small beaker, and warm the mixture by lowering the test tube into the beaker of warm water. Observe the flashes and small explosions that occur a t the boundary of the two liquids. After a few minut,es add anot,hre small port,ion of the permanganate to the tuhe to cause a new series of flashes. Caution: Do not use more than the 0 1 g of KMn04 add zt only zn very small amounts and slowly. Be e the reaction has ended and the contents of the test tube have cooled before pouring into a large quantity of cold wat,er. REMARKS
The permanganate in t,he presence of the sulfuric acid furnishes the oxygen necessary for the rapid combustion.
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March I960
2 of Chemical Education
TARS AND RESIDUE IN CIGARETTE SMOKE
Submitted by: A S Chatfield, St. Petersburg Junior College, St. Petersburg, Florida Checked by:
Joseph M. Denhad, IIiram College, Hiram, Ohio
PREPARATION
Mount a cigarette in a drying tube (CaCls-type) that is partially filled "ftith glass wool The cigarette may be unted in a section of 10 mm glass tubmg, inserted in ork stopper. Connect the drying tube to an aspirator pump and trap assembly or to a siphon bottle. Provide watch glasses and ethyl ether solvent.
the cigarette has been consumed to within one-quarter inch of the filter, or an eqi~ivalentdistance for nonfilter cigarettes, disconnect the drying tube containing the glass wool and extract the tars and residue by pouring several small portions of ether (until glass wool is nearly colorless, 10-15 ml total) through the tuhe holding the glass wool. Allow the extractions to drain int,o an evaporating dish. Fi1t.w units may be placed in another dish and ext,racted with ether to demonstrate their effectiveness in trapping the tars. After evaporation of the ether is complete, compare the results by observing the residue in the evaporating dishcs. REMARKS
DEMONSTRATION
Start suction through the system, light the cigarette, and regulate suction to maintain slow burning After
I t is especially instructive to pass the evaporating dishes among the students so they may notice the odors associated with the residues.
Journal of Chemical Educat-tun
.
Mar^12 1960
