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Denisan University Granville. Ohio 43023
Synthesis and Decomposition of Zn12 Submitted by:
Checked by:
Noojin Walker Pensacola Junior College Pensacola, F L 32504 Richard F. Jones Sinclair Community College 444 West 3rd Street Dayton, OH
Preparation Obtain Zn dust (3 g), Iz crystals (2 g), water (10 ml), small gauge insulated Cu wire (30 cm), two 100 mm watch glasses, dropper, funnel, filter paper, stirring rod, and a DC power source, (1.5 V AA dry cell is the minimum.) Demonstration 1) Mix the Zn and 12 on a dry watch glass. No reaction. 2) Add 10 ml of water drop by drop (hood).Copious violet vapors. 3) Stir the mixture well. Filter. Pour the filtrate into a watch glass. The solution should he relatively clear and colorless. 4) Connect Cu wires to the DC source. An amber coloration of the filtrate occurs immediately at the anode; Zn accumlatea on the cathode. Remarks The simplicity, the controlled violence, and the visual excitement makes ZnIp an excellent demonstration. In a very few moments it can he used to show direct combination, decomposition, the effect of a catalyst, recrystallization of sublimed 1%and electrolysis. The demonstration is enhanced by the use of an overhead projector. The violet color is more dramatic, the silvery sparkles of cjstalline I2 in the violet vapors are visible, amber droplets of aqueous I p are apparent, and the produds accumulating around the electrodes and the diffusion rates are easily observed ("Tested Demonstration," 6th ed., p. 161). The reaction is reported to occur also when scrupulously clean and dry Al and Mg are used (Antelman, M., J. CHEM. EDUC., 30, 134 (1953)). What would he the electrolytic products?
788 1 Journal of Chemical Education
The Preparation and Properties of Poiybutadiene (Jumping Rubber) Bassam Z. Shakhashiri Glen E. Dirreen and Lloyd G. Williams' University of Wisconsin-Madison Madison, WI 53706 A violet suspension of an "alfin" catalyst is added to a pop bottle containing a solution of 1,s-hutadiene in pentane. The bottle is corked and shaken for several seconds. The mixture sets to a gel and the contents erupt from the bottle within two minutes.
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T H E CHEMICALS USED I N THIS DEMONSTRATION ARE FIRE HAZARDS.
Materials Jumping rubber kit available from Orgmet, Inc., Route 111, East Hampstead, NH 03282 The ....kit: .....
Small pop b o k mntainii l$-hutadiene digsolved in dry pentane War-sealed, screw capped bottle containing the alfin catalyst Cork for pop bottle Bottle opener Glass stirring rod Tonga Procedure WARNING! The alfin catalyst is extremely reactive with moisture. Perform this demonstration in a well-ventilated room to minimize inhalation of pentkne vapor. Open the catalyst vial and use the glass rod to stir its contents. Quickly remove the crown seal from the pop bottle and add all the catalyst. Immediately cork the bottle and shake. The temperature increases slightly (to about 50°C) and the pressure increases (perhaps 2-3 atm) until, within two minutes, the cork is forced from the mouth of the bottle and a polymer "snake" shoots out into the air. The hottle is left al-
' Present address: Hampshire College, Amherst, MA 01002
