Vol. 3 , No. 1 The Chemical Educator © 1998 Springer-Verlag New York, Inc.

ISSN 1430-4171 http://journals.springer-ny.com/chedr S 1430-4171(98)01182-5

Classic Chemical Demonstrations. Compiled by Ted Lister. Royal Society of Chemistry, London, 1996. xvii + 284 pp. ISBN: 1 870 34338 7. $58.00 from ACS, Washington DC, or 27.50 pounds sterling from the Royal Society of Chemistry.

This compilation of 100 demonstrations may be a good choice for teachers who are overwhelmed by the thousands of demonstrations that have been published, and would like to start with proven "standards." True to the title, these demonstrations are mostly well-tested classics suitable for high school or college general-chemistry courses, and will be familiar to experienced teachers. They include oscillating reactions, the "Old Nassau" clock reaction, "alcohol guns," silver mirrors, the ammonium dichromate volcano, the "nylon rope trick," the thermite reaction, luminol chemiluminescence, the "blue bottle" experiment, a sodium acetate "stalagmite," anodizing aluminum, the ammonia fountain, the photochemical reaction between H₂ and Cl₂, and the catalytic oxidation of ammonia. The procedure for each demonstration is clearly written and well-illustrated. Literature citations and a brief statement of background theory are sometimes included. The introductory material includes a table listing the demonstrations, their level (pre- or post-16), and their relevance to 11 categories ranging from entertainment to thermodynamics.

Unfortunately for the less-experienced demonstrator at whom this book is aimed, the safety caveats it contains are meager. A listing of 69 substances used in the demonstrations, each with a short phrase about hazards, is probably not adequate to meet current safety standards. The less classic demonstrations (such as sprinkling KMnO₄ into a mixture of ethanol and hydrogen peroxide to produce explosions) may pose hazards that are underemphasized. Some of the warnings that have accumulated in the literature for classic experiments are not included. Nowhere are the special hazards [1] posed by the peroxide layer found on aged potassium noted, although several experiments require the metal. Statements like "Care is needed when handling liquid oxygen and some teachers may prefer to omit this part of the experiment," presented without helpful citations, seem contrary to the attitude that a good demonstrator should have [2]. One should want to know what the dangerous properties of liquid oxygen are, and under what conditions it can be handled safely.

A few of the demonstrations in this volume are less well known, including a study of the equilibrium ICl (l) + Cl₂ (g) « ICl₃ (s), catalysis of the reaction Na₂S₂O₃ + H₂O₂ ® Na₂SO₄ + H₂SO₄ + 3 H₂O by ammonium molybdate, deflection of electrolytically produced ions in a magnetic field, and measuring the temperature dependence of the conductance of silicon. These are interesting demonstrations with clearly written, apparently reliable procedures that deserve notice.

It is interesting to compare the treatments of the classic demonstrations in this volume with the descriptions in other compilations; treatments of the thermite reaction are typical. Lister recommends about 43 g of mixture in a 16 x 150 mm test tube, ignited with magnesium ribbon and powder in a solid, reasonably safe procedure. The theory section includes only the overall reaction and its enthalpy change and provides a single reference; safety warnings include having a sand bucket and (non-water-type) fire extinguisher on hand, and wearing safety goggles. Five procedures are given in Gilbert [3], with six references, but no thermodynamic data are provided. Several important safety caveats are given, including a warning about explosions that can occur if the iron is allowed to drop into water. As noted recently [4], this may release and ignite hydrogen in a manner similar to explosive reactions observed at nuclear power plants. Shakhashiri [5] provides two procedures (with comments on others), eight references, and a thorough discussion with the overall equation, a discussion of the thermodynamics of the reaction based on the enthalpies and entropies of formation of the reactants and products, and deduced free energy change for the reaction, as well as comments on the unfavorable entropy change. Shakashiri also includes comments on the use of metal oxides other than Fe₂O₃ and warnings about explosive reactions that have been observed with CuO and Mn₃O₄ and aluminum. Treatments of other demonstrations by the three compilers follow about the same pattern.

It is hard to resist discussing treatments of the NO₂-N₂O₄ equilibrium. Here, the standard Lister disclaimer "It is the responsibility of teachers doing this demonstration to carry out an appropriate risk assessment" is clearly inadequate. The reaction of asthmatics and others to the gas up to one day after exposure, as well as the acute toxicity of the gas, should be mentioned, especially since it is of environmental interest. While Lister's treatment, incl chemical formulas and alternate names are always provided to avoid confusion over chemical nomenclature. Some U.K. English terms may be confusing to those, such as Americans, who do not speak the language. No list of sources is included, so for example, it helps U.S. readers not a bit to know that Tasco supplies firelighter (used in the reduction of CuO by methane, p 133), because an address is not given for the company, and American firms would not be likely to know what "firelighter" is. Some of the references given under "Further Details," such as a chemistry teachers' guide [7], are not readily available outside Great Britain.

This paperbound volume does not lie flat to allow convenient use while preparing demonstrations, in contrast with the spiral-bound two-volume set edited by Gilbert et al. [3], which is the most comprehensive compilation with close to 1000 demonstrations, the spiral bound two-volume set by Ealy et al [8, 9] (close to 200 demonstrations), or the clothbound four-volume set by Shakashiri [5] (over 300 demonstrations with exceptionally thorough documentation). The binding will probably not stand up under heavy use as a reference work. This is the only demonstration book of note that has no index.

References

2. See, for example: Bodner, G. M. "Lecture Demonstration Accidents from which We can Learn" J. Chem. Educ. 1985, 62, 1105. Reprinted in reference 3, p T-4.

3. Tested Demonstrations in Chemistry; Gilbert, G. L., Alyea, H. N.; Dutton, F. B.; Dreisbach, D. Eds. Published by arrangement with the Journal of Chemical Education, and available for $60 in the US and $66 outside the US from Dr. George Gilbert, TD-Text, Denison University, Granville, OH 43023.

4. Chem. Eng. News; May 14, 1990; p 2.

5. Shakhashiri, B. Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry, Volumes 1–4; University of Wisconsin Press: Madison, WI; 1983–1992.($25 each, or four volumes for $90).

6. Yang, Z., J. Chem. Educ. 1993, 70, 95.

7. Revised Nuffield chemistry teachers' guide II; Longman: London, 1978.

8. Ealy, J. L. and Summerlin, L. R. Chemical Demonstrations: A Sourcebook for Teachers; American Chemical Society: Washington, DC, 1988; Volume 1.

9. Summerlin, L. R.; Borgford, C. L.; Ealy, J. B. Chemical Demonstrations: A Sourcebook for Teachers; American Chemical Society: Washington, DC, 1988; Volume 2.