ChemDemos II is a laser videodisc that includes 39 demonstrations suitable for use in introductory chemistry classes either at the high school or college level. As in the original ChemDemos Videodisc (1) the emphasis is on the chemistry, with most demos shown close up, full screen. In only a few cases, where scale is important, can more than the demonstrators' hands be seen. Each demo has been selected because it illustrates an important aspect of chemistry, involves substances or equipment that are not available in many schools, and/or is hazardous or causes problems of disposal or cleanup. Some demos are brand new and not yet published; others are old standards, sometimes with a new twist. All are certain to stimulate students' curiosity and help them learn.

The Belousov-Zhabotinskii reaction, featured on the cover, oscillates in both time and space. It is a complex system involving bromate, bromide, malonic acid, sulfuric acid, ferroin indicator, and oxygen. The oscillations in this reaction start with the formation in a red solution of small blue dots that expand in ever-widening concentric rings.

ChemDemos II includes a voice-over explanation of what is happening in each demo. Chemical formulas and equations are provided on screen whenever appropriate, and more complete explanations of the demonstrations, the principles they illustrate, and their practical applications are given in printed documentation. The sound of a demo is included when it is important. Examples include the Conductimetric Titration and Piezoelectric Effect. The voice-over can be turned off so that teachers can provide their own descriptions, explanations, and discussions of each demo.

Several of the demos are accompanied by computer-generated animations that provide microscopic explanations of the macroscopic phenomena observed. Examples include Electrolysis, Peeling Layers of Molybdenum Disulfide, and Memory Metal.

Several of the demos illustrate processes that are of practical importance. Among these are the Cathode Ray Tube, utilized in TV and computer monitors, and Heat Treatment of a Metal Bobby Pin, which demonstrates the effects of the annealing and tempering processes. Demos are grouped on the videodisc according to topic. Each demo can be accessed quickly and easily using a hand control for the videodisc player and the frame numbers included in the documentation. Bar codes are also provided in the documentation so that users with bar-code readers have easy access to each demo. A text file that can be incorporated into JCE: Software's Videodisc Browser 2.0 for either Macintosh (2) or Windows (3) is included so that those with computer-controlled videodisc players can click on a demo's name to displayed it. The contents of the disc are listed below:

Side 1

Gases and Liquids

• Fluidity of Gases
• Effusion of Gases
• Gas Volume
• Boiling by Cooling
• Critical Point of Benzene
• Viscosity of Liquids

Solid State

• Simulation of Dislocations in Metals
• Heat Treatment of a Metal Bobby Pin
• Heat Conduction by Diamond
• Hardness of Solid Substances
• Piezoelectric Effect
• Superconductivity
• Paramagnetism: Oxidation States of Manganese
• Curie Point of Nickel
• Ferromagnetic Fluid
• Thermochromism: Mercury(II) Iodide
• Memory Metal

Rates of Reactions

• Thermodynamic vs. Kinetic Control: Forming HgI₂
• Temperature and Reaction Rate
• Visible Intermediate: Tartrate + Peroxide
• Autocatalysis: Permanganate + Oxalate
• Iodine Clock Reaction
• Oscillating Reaction: Briggs-Rauscher
• Oscillating Reaction: Belousov-Zhabotinskii

Electrochemistry

• Pulsating Electrochemical Reaction: Hg Beating Heart
• Oxidation States of Vanadium
• Halogen/Halide Redox
• Electrochemical Series: Metal Trees
• Overvoltage
• Metal/Iodine Reaction and Cells
• Simulated Lead Storage Battery
• Electrolysis of Water
• Electrolysis of Aqueous Solutions
• Cathode Ray Tubes
• Conductimetric Titration

Chemical Properties

• Chemical Properties of Sulfur Dioxide
• Relative Reactivity of Alkali Metals
• Sodium + Chlorine
• Potassium + Bromine

Hardware and Software Requirements

ChemDemos II is a 12-in., double-sided, 60-minute, CAV-type videodisc in NTSC format (it is incompatible with the PAL standard used in many European countries). It may be operated from any videodisc player using a hand-held remote-control keypad or a barcode reader. (Consult the supplier of your videodisc player to ascertain whether it can be used with a barcode reader.) To make the video presentation visible to students in a classroom either a large-screen color monitor or a color video projection unit with sound output is needed. The size of the monitor (or the need for a projection unit) depends on the size of the class to which the presentation will be made. If the disc is to be used under computer control the videodisc player must have a serial (RS-232) interface. A text file for the videodisc compatible with Videodisc Browser 2.0 for both Macintosh and IBM compatible computers is included.

Acknowledgement

The following people contributed significantly to the development of this videodisc. Their assistance is gratefully acknowledged: Ron Perkins, Greenwich High School, Greenwich, CT; Doris Kolb, Bradley University, Peoria, IL; George Hardgrove, St. Olaf College, Northfield, MN; and Eric Bode Jacobsen, University of Wisconsin-Madison, Madison, WI.

Literature Cited

1. Moore, J. W., Jacobsen, J. J., Hunsberger, L. R., Gammon, S. D., Jetzer, K. H., Zimmerman, J. ChemDemos Videodisc, J. Chem. Educ.: Software, 1995, Special Issue 8.
2. Jacobsen, J. J. Videodisc Browser 2.0, J. Chem. Educ.: Software, 1995, 7C, No. 2.
3. Jacobsen, J. J. Videodisc Browser 2.0, J. Chem. Educ.: Software, 1996, 3D, No. 2.
4. HyperCard, Apple Computer, Cupertino, CA 65014-2084.
5. ToolBook, Asymetrics Corp., Bellevue, WA 98004.

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