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A commercially available chemiluminescent system is used to produce a yellowish-green cold light which is easily visible in a darkened room. The light, which is initially bright enough for reading, gradually fades over a period of about 12 hours. MaterialsThree CYALUME® (Trademark of American Cyanamid Company) lightsticks; may be obtained from the Ventron Corporation (Alfa Products), the Aldrich Chemical Company, or Markson Science Inc. In the Midwest, the lightsticks are also available in some hardware stores and gasoline filling stations.beaker, 500 ml (2) ice, 500 ml hot water, 400 ml Procedure To observe the chemiluminescence, follow the instructions on the package (bend the plastic tube slightly to break the thin vial inside, and shake). Since the light is generated without heat or flame, the "cool-light" source may be passed around the room to enable students to inspect it more closely.

When liquid nitrogen is poured between the poles of a powerful magnet, the liquid is not held in the pole gap. When liquid oxygen is poured between the poles of the magnet, some of the liquid is held in the pole gap until the liquid evaporates. This demonstration also displays the characteristic blue color of liquid oxygen. MaterialsLiquid nitrogen (5-8 1) 02 gas (cylinder with pressure regulator) 2 Dewar flasks (11 capacity) Large test tube (38 mm o.d. X 300 mm long) Ring stand and clamp to hold the large test tube Rubber tubing (7-8 mm o.d. X 30 cm long); 2 pieces Glass tubing (7-8 mm o.d. X 30 cm long) Glove (to protect hand from cold) Permanent magnet Copper coil Unsilvered Dewar, 250-ml capacity (optional) 250 ml beaker cigarette (optional) Several types of magnets may be suitable for this demonstration. The permanent magnet used at the University of Wisconsin-Madison is a "Horn Gap" magnet with an original field strength of 1.8 kilogauss. Conical pole pieces machined

Reagents are added in a specified order to a large beaker containing an aqueous solution of sodium carbonate. Ag2C03, Ag20.H20 or AgOH, AgCl, Ag(NH3)2+, AgBr, Ag(S203)I~, Agl, Ag(CN)2 and Ag2S are prepared. The sequential formation of each precipitate and complex ion is used to demonstrate how solubility of silver(I) compounds is related to Ksp values and the formation of soluble complex ions. An alternate procedure may be used. MaterialsProcedure A 600-ml beaker magnetic stirrer with stirring bar graduated cylinders, 10-ml, 50-ml and 250-ml 200 ml distilled water 1 ml 0.1 M Na2C03 10 ml 0.1 M AgN03 10 ml 0.1 M NaOH 30 ml 0.1 M NaCl 35 ml 5.OJWNH3 10 ml 0.1 M NaBr 50 ml 0.1 M Na2S203 10 ml 0.1 M KI 20 ml 0.1 M KCN 10 ml 0.1 M Na2S or (NH4)2S ProcedureB 1 1000-ml beaker, preferably with approximate graduations 9 150-ml beakers graduated cylinders, 10-ml, 25 ml, 50-ml and 100-ml 10 glass stirring rods 800-ml distilled water 10 beakers of sufficient size to hold the following solutions (100-ml beakers are convenient): 4 ml 0.