An investigation of the Blue Bottle Experiment, a well-known lecture demonstration reaction involving the dye-catalyzed air oxidation of a reducing sugar in alkaline solution, has delineated the sequence of reactions leading to the bleaching of the dye, the regeneration of color, and so forth. Enolization of the sugar is proposed as a key step in the sequence. The first-order rate constant for this step was found to be ∼2.3 × 10 −3 min −1 with respect to total sugar concentration under the conditions used (0.184 M glucose, pH 13.3, 25°C). Measurements with an oxygen-sensing electrode on Blue-Bottle mixtures containing varying quantities of methylene blue indicated that in a usual demonstration the rate of O 2 consumption is ∼60% of the enolization rate. Small samples of the organic oxidation product were isolated and found by chromatographic and NMRspectroscopic examination to consist primarily of the 5-carbon sugar acid arabinonic acid.

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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

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.