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A chemistry show without the magic.

This article looks at a chemistry show which conveys the wonder of the science by using examples from everyday life.

The name most closely associated with the founding of popular chemistry presentations is that of Joseph Priestley [1]. Priestley, in the closing decades of the eighteenth century, endeavoured to show the advances in chemistry to the citizenry by means of public lecture-demonstrations in many of the major British cities. Some of these performances were held at the famous Royal Institution, London, where the demonstrations of Priestley's successor, Sir Humphry Davy, have been immortalized in an engraving that shows a deranged-looking Sir Humphry dispensing laughing gas to a somewhat raucous audience. And this is the popular perception of a chemistry show: a performance designed to bring entertainment to the masses. Such shows have continued to be popular into the twentieth century [2] and will, no doubt, continue to be popular for decades (and centuries) to come.

Chemistry as Entertainment

It may be argued that there is a place for chemistry as pure entertainment. Unfortunately, chemistry as amusement, or "chemical magic" as it is sometimes called, carries with it a message that can be very counter-productive to the image of science. Magic involves purposeful illusion and deception while science, on the other hand, provides a serious attempt to explain reality [3]. Thus the term "chemical magic" itself suggests that chemistry is a supernatural phenomenon. Series of demonstrations without explanation, such as the generation of pretty colours, of fires, and of the occasional explosion, blur the distinction between science and pseudo-science. To the lay person, there is not much of a philosophical difference between the alchemical-style conversion of a copper penny to "silver" and then to "gold" and the apparent bending of spoons by mental powers. As well, by watching these shows, members of the public identify chemistry as a superficial activity rather than as one of the leading contributors to our current civilization. Is there any other human endeavour where the public image is so dissociated from reality [4]?

It is also the image of chemists that is affected by these types of shows. The audience perception of the chemist-showman/woman is that of a rather frivolous, eccentric individual (especially if the presentation is replete with frequent explosions and flames) - a member of an elite, rather like a real magician or a traditional alchemist, whose knowledge enables the chemist-presenter to "turn water into wine" among other "tricks", but who keeps the secret of his/her skills within the ranks of those known as chemists.

It is possible to present interesting chemistry in a more positive manner. For example, though there are significant shortcomings in their presentations, the various North American science television shows for children tend to present chemistry in a realistic light [5]. In Montreal, the team of Fenster, Schwartz and Harpp have offered a program of evening public lectures in which demonstrations were used to illustrate socially-important applications of chemistry [6]. Nevertheless, the perception of chemistry as "bangs and smells" produced by somewhat demented individuals is still alive and well.

The Contrast of the High School Experience

At the other end of the spectrum, high school chemistry programs strongly emphasize chemical principles over chemical applications. The mole calculation becomes the focus of the chemistry courses (as it is at the college/university level [7]) and hence students obtain the perception that chemistry is an endless purgatory of mole conversions. In this way, students dismiss chemistry as a boring, mathematical-focused subject that is totally irrelevant to their lives. This viewpoint is probably less widespread in urban areas where student groups can visit local science centres. However, in remote areas, such as the west coast of Newfoundland, the possibility of students seeing "chemistry in action" is minimal. A less-than-ideal substitute for seeing chemistry is to read about chemistry, yet here too, rural students are at a disadvantage, with the science section (if it exists) in the local bookstore (if there is one) containing books on the excitement of astronomy, biology, geology, and so on, but rarely even one tome expounding the fascination of chemistry [8].

Activities at Grenfell College

For many years I have been dismayed by the students' belief that chemistry only exists in chemistry labs [9] and I have been determined to combat this viewpoint. By means of a two-fold strategy, a Fall semester 'Chemistry Essay Competition' and a Winter semester 'Chemistry and Everyday Life Presentation', I believe that, in western Newfoundland, I have helped open the students' minds to the relevance of chemistry. The Chemistry Essay Competition stimulates each student to research and write a comprehensive well-structured report on interesting aspects of a particular element or compound. This aspect has been described previously [10,11] and it continues to be successful.

Though delving through encyclopedias and other source books looking for chemical information can be interesting, chemistry is a very visual science, and it is with images as well as with words that we describe chemical processes and changes. Unfortunately, with the pressure of teaching commitments, few high school science teachers have the time, facilities, or knowledge-base to provide illustrations or demonstrations that make chemistry more than an abstract subject. As a result, students do not obtain an appreciation of how the principles covered in their high school courses can be illustrated in a very visual manner and that the principles do, in fact, have applications to their everyday lives.

The Chemistry and Everyday Life Presentation developed in a more convoluted manner than the Chemistry Essay Competition. During the 1980s, science safety became a major issue in Newfoundland schools and as a result of visiting high schools with a 'Science Safety Road Show' [11], I developed contacts with many of the high school chemistry teachers. Following conversations with the teachers, I received requests to visit several of the schools to give a presentation on some aspect of chemistry. I had always had an. interest in demonstrations that illustrated chemical principles [12], thus I had a repertoire to hand. At the same time, I had a set of slides of unusual applications of chemistry that I had assembled for photos in my two coauthored high school texts [13,14]. Therefore, it was relatively easy to put together a slide/demonstration show that could be taken to a school and rapidly deployed. This presentation was quite popular, but the number that I could give was limited by the number of days that I could spare from teaching, scholarly, and committee duties, in order to drive to schools that were up to 250 km away.

In 1992, I arranged for David Katz to visit the College and give his famous presentation on 'Chemistry in the Toy Store'. This was presented in two performances in the College Theatre and I was pleasantly surprised at the number of schools that sent bus-loads of chemistry students to the show. The following year, I arranged to give my own 'Chemistry in Everyday Life Show' in the Theatre setting. This method had three advantages over the earlier format. First, it was possible to handle a far larger number of students than was possible in periodic forays to individual schools. Second, with the assistance of the chemistry technical staff, it was possible to prepare and present a wider range of demonstrations than those that could be crammed in the back of a vehicle. Third, the presentation was no longer limited to a single school class period. The Theatre format has proved very successful and four performances are now offered each year, providing a capacity for up to 800 students. Several of the participating schools are a considerable distance away; the record to date being held by the students of Mary Simms All-Grade School who travelled from Main Brook to Corner Brook, a distance of 433 km each way!

The Chemistry and Everyday Life Presentation

As my presentation does not consist of the typical collection of chemical demonstrations, I will describe a selection of the topics and demonstrations that I cover. I start by emphasizing how new discoveries in chemistry will change our lives in the millennium to come. It is materials chemistry, the synthesis of new and novel materials for specific roles in our lives, that I argue will be the most manifest aspect of chemistry in people's lives. To illustrate, I demonstrate nitinol - "Memory Metal" [15] - straightening a piece and then plunging it into boiling water, causing it to revert to its original shape. Next, I demonstrate the incredible strength of Kevlar [16] by suspending a total of 4 kg in weight from a single strand. The emphasis here is on the many uses of this fibre, such as its life-saving role in bulletproof vests for police officers. For another demonstration, I describe how relatively small changes in molecular structure can produce major changes in properties. For this purpose, I demonstrate the "happy/unhappy balls", neoprene and polynorbornene, and discuss their different uses [17].

Following this introduction, the remainder of my presentation relates closely to the topics and sequence covered in the high school curriculum. I start with the topic of the Law of Constant Composition, showing a slide of two bottles of vitamin C, one containing half as many tablets than the other, yet costing even more. The far more expensive bottle contains "natural" vitamin C. I describe how people are fooled into thinking that "natural" vitamins are somehow more powerful than synthetic [18], yet the Law tells us that all ascorbic acid molecules are chemically identical, regardless of source (though one has to be careful with this statement, as biosynthetic vitamin E contains only the active stereoisomer whereas the chemosynthetic compound is a racemic mixture [19].).

I show how chemistry is interwoven with art and architecture through a slide of M.C. Escher's print 'Cubic Space Divisions' which relates to the simple cubic lattice packing and one of the Atomium, the enormous representation of magnesium atoms in a crystal, at Brussels. I point out that in these cases, art followed science while the geodesic dome shape, such as the former U.S. pavilion at Expo, Montreal, predated the discovery of the similarly-shaped third allotrope of carbon, the buckminsterfullerenes [20]. My final slide on crystals and molecular structure relates to the marvels of the natural world, in particular the tough, fracture resistant spines of sea urchins. These consist of near-perfect aligned microcrystals of calcium carbonate with small proportions of protein fibres providing a very strong composite material [21].

The next high school topic I discuss is the simple Bohr model of the atom. I describe how electrons can be given energy in a variety of ways, producing excited states. The electrons can then return to the ground state, emitting electromagnetic radiation in the process. First of all, I perform the common flame test using sodium and lithium chlorides. After describing what is happening on the sub-atomic scale, I mention the use of this technique as an analytical tool in environmental chemistry and of the use of element emissions in fireworks [22]. Following this, I demonstrate the "electric pickle" [23] and point out that the yellow colour indicates the high level of sodium in the electrocuted pickle. I urge students not to try that experiment at home! Then I use a long-wave ultraviolet light to illustrate the use of UV light to excite the electrons. As examples of fluorescence, I use tonic water, detergent powder [24], a selection of fluorescent minerals, and postage stamps. I finish this topic with a display of phosphorescence using a set of solid phosphorescent samples, a fluorescent safety Exit sign, and a periodic table T-shirt on which the radioactive element symbols "glow in the dark".

The next topic is bonding and intermolecular forces. I start with a slide of an aerogel, an ultra-low density material whose framework structure consists of very strong silicon-oxygen covalent bonds [25]. Next, I describe how dry cleaners are not dry - that they use low polarity solvents to remove oil and grease stains [26]. Once more I look at the biological world, the ice fishes around the Antarctic that are able to live in water below 0 [degree] C by virtue of the hydrogen-bonding polyglycol molecules that they synthesize [27]. Then I contrast the vitamins B and C with vitamins A, D, and E. Vitamins B and C are quite polar and hence prefer hydrogen-bonding solvents such as water. Excessive intake of these vitamins is safely urine-excreted while the low-polarity vitamins A, D, E, and K tend to accumulate in the fatty, tissues of the body where they can accumulate to toxic levels. From biochemistry it is on to archaeological chemistry; the preserving of the sunken warship, the Wasa, by means of polyethylene glycols, again illustrates the phenomenon of intermolecular forces; in this case, hydrogen bonding [28]. Finally, displaying a slide of the bust of Egyptian queen, Nefertiti, I point out the importance of the cosmetic chemical industry and its reliance on bonding and forces, for example, the low polarity of lipstick materials [29].

The theme of intermolecular forces is continued in a series of demonstrations. Hydrophobic materials are illustrated using a paper towel sprayed with a water-repellent shoe spray and with "magic sand" [30]. For hydrophillic materials, the water-absorption properties of diapers is always popular [31] as is the addition of a small amount of poly(acrylamide-co-sodium polyacrylate) "A.S.A.P." [32] to a large volume of water, rapidly producing a gel (much more quickly than with diaper filling). Solid sodium chloride is then added to the gel, liquefying the material and showing that the hydrogen bond network in the gel can be broken by the effects of the salt ions.

The next topic is chemical reactions, such as those that produce a precipitate. I illustrate this category by the formation of lead(II) chromate (used for highway markings) and barium sulfate (used for stomach X-rays). I show that chemical reactions can produce heat using one of the super-saturated "hot packs" on an overhead projector [33]; electricity with the "potato porcupine" [34]; and light with a Cyalume[R] stick. This leads into the topic of rates of reaction, which I illustrate using the reaction of Alka-Seltzer[R] tablets with hot and cold water. I extend the discussion of temperature and reaction rate by mentioning the misuse of analgesics to reduce fever [35]. This section is closed with a mention of enzyme catalysis the traditional use of pineapple to soften meats, a use that has continued with tinned pineapple even though the heat treatment of the canning process destroys the enzyme and hence the original reason for adding the fruit [36].

The next topic in most high school programs is equilibrium, particularly equilibria that involve acids and bases. I describe how sodium hydroxide is used in a variety of food processing contexts, such as the processing of olives [37], tinned potatoes, grits, and pretzels. Next, I demonstrate that many household cleaners are, in fact, quite concentrated acids or bases by adding universal indicator to samples of SaniFlush[R] and Drano[R]. I warn the students that such solutions are extremely corrosive and should be handled with utmost care. Our homes also contain indicators, and I prepare and test a solution of powdered Life brand Laxative tablet[R] which uses phenolphthalein as its active ingredient.

Reverting to slides, I show a photo of Lake Nyos and describe the disastrous release of the acidic gas, carbon dioxide, that had previously been trapped in the deep waters in its solution phase under pressure [38]. I mention that liquid carbon dioxide is used as a solvent to remove caffeine from coffee in supercritical fluid extraction. Which brings me into the basic nature of caffeine and its presence in a wide variety of household products such as coffee, tea, colas, "wake-up" pills, and many analgesic formulations. From acids and bases, it is on to oxidation and reduction, with the use of bleach (sodium hypochlorite) as an oxidizing agent and lemon juice (ascorbic acid) as a reducing agent in the home. I close the redox section by showing a slide of the life in the deep sea vents and I point out that vent life is based on chemosynthesis for its energy, not photosynthesis [39].

Though radioactivity and nuclear chemistry are often part of school chemistry curricula, I limit my mention of this topic to the display of a smoke detector. The detector contains an isotope of an element (americium-241) that was synthesized in the laboratory and that does not occur naturally to any measurable extent [40]. Without this synthetic element, fire detection would be much more difficult. Many people forget that every radioactive element decays and that a smoke detector has a finite lifetime (the "good until" date usually stamped in the plastic case) beyond which the remaining amount of radiation from the americium is too low to activate the smoke detector. The disposal of old smoke detectors should be by return to the manufacturer rather than placing them in the garbage.

The performance concludes with the organic segment of the show. I start by discussing the importance of carbon-carbon double bonds in our diet. I show how we can use an aqueous bromine solution to identify the presence of double bonds in cooking oil and in tomato juice [41]. Then I link the topic back to the earlier discussion on intermolecular forces. I point out that we eau remove the unhealthy saturated fat from ground meat by using unsaturated oils as a solvent [42] and, as emphasis, I show the extracted semi-solid mass of fat from a sample of about 1 kg of ground beef. This produces various noises of disgust from the audience and I have the hope that at least some students might return home to use this technique of fat removal in their own households.

From the demonstrations, I show the last set of slides. First, ripe and unripe bananas which I use to describe the role of ethene gas in their ripening. Now we understand the importance of the gas, we can use it to control the ripening process in fruits [43]. Then I display some foods, including parsnips and green potatoes and explain the natural carcinogens present in them [44]. Following this, I show a slide of the rosy periwinkle, a source of one of the most potent anti-cancer agents [45], and relate how we rely heavily on natural products, particularly those from the wide biodiversity of the tropics, for many of our medicinal sources.

The closing demonstrations relate to polymers. In the past, I produced a polyurethane foam but with its high toxicity [46], I now produce rubber from latex liquid [47]. The final demonstration is the use of acetone to dissolve Styrofoam[R] cups [48]. This demonstration again demonstrates the importance of intermolecular forces.

The Future

The previous section described some, but not all of the demonstrations and slides that I have assembled for my show. In the show, every demonstration or slide has to have some interesting or relevant aspect to it and every year there is something new (or old) to try.

Over the years, I have obtained much satisfaction from the efforts that I have put into the presentation and it is particularly rewarding when I am approached months or years later by an individual who recognizes me from the show and thanks me for the stimulation that they received from it.


The presentations would not have been feasible without the enormous amount of preparation performed by the chemistry technicians, Wanda Ellsworth, Wade Goulding, and Maureen Haines. Dale Power is thanked for operating the lighting and sound facilities in the Theatre. Julian Dust, MCIC is thanked for his critical review of the manuscript.


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47. Hocking, M.B. and Rayner Canham, G.W., 'Polyurethane Foam Demonstrations: The Unappreciated Toxicity of Toluene-2,4-diisocyanate [TDI]', J. Chem. Educ., 51:A580-A581, 1974.

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Rayner-Canham, FCIC is the recipient of the 1996 F.A. Aldrich Award of Memorial University of Newfoundland for his contributions to science education (including the Chemistry Presentation) in the province.
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Title Annotation:chemistry presentations
Author:Rayner-Canham, Geoff
Publication:Canadian Chemical News
Date:Mar 1, 1998
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