This web site was split on 1/30/21 into two
websites, this page (http://murov.info/chemdemos.htm)
The latter site includes a different narrative and emphasizes the American flag demo.
For many more websites by this author, please visit: http://murov.info
Free downloadable lab book for the college level organic chemistry course just posted 02/27/14.
Experiments and Exercises in Organic Chemistry: A Challenge Oriented Approach - http://murov.info/orglab.htm
The Internet contains a substantial number of sites related to chemistry. A number of sites give information about chemical demonstrations. Some of these are available in the parent site (http://murov.info/webercises.htm) and in the list below.
While the discussion presented below does include instructions for some chemistry demonstrations, the intention of this Internet site is not to provide an extensive set of demonstrations but to provide some ideas for presentation style and technique and also an anticipation of audience response.
The following sites contain chemical demonstrations:
http://www.chymist.com/magic into science.html
Safety in Chemical Demonstrations
http://www.chymist.com/Safety with chemical demonstrations.html
Two types of presentations are discussed below.
In addition, instructions for performing an
flag demo and more ways to interact with an audience have been added at:
1. "FLASH, WOBBLE AND GLOP" is an educational type of presentation that is suited for audiences of about one to three classes (30 to 90 students). It works best at about the fifth grade level but can be adapted to any age level. The discussion stems from giving this presentation hundreds of times.
WOBBLING AND GLOPPING TO HOLIDAY MUSIC" or similar has only been given a
few times and has been
designed with entertainment in mind rather than education.
FLASH, AND GLOP or How to Turn Children on to Chemistry in 45 Minutes
In a world with science-based decisions a significant part of our everyday lives, it is important that educators make every effort possible to increase and improve scientific awareness and education. One route towards the accomplishment of this goal is to cultivate interest in science in elementary and middle school children. A chemistry presentation perhaps taking only 45 minutes tends to be the kind of experience which leaves a lasting and favorable impression with children. The goal is not to produce chemistry majors but simply to encourage children to appreciate and investigate scientific issues and questions.
This paper will attempt, by giving some of this author's presentation techniques and some written student responses, to encourage more chemists to offer assistance and programs for local schools. This chemistry presentation is easily developed, portable (the presentation is often given off campus but everything can be put into one cardboard box), and does not require the talent, flare or courage of a Hubert Alyea or the group "Weird Science". Each demonstration has been selected because of educational as well as fascinating and ease of use and preparation features. It is quite a rewarding and enjoyable experience to watch the mystified expressions of children and to hear them "ooh" and "ahh" as the demonstrations are performed.
The presentations begins with comments on the scientific method and the key role that observation has in the process. It should be pointed out that we make observations using all of our senses and the good scientist takes great care to make complete, unbiased observations and to pay special attention to the unexpected. Sometime during the demonstration, the issue of safety should be discussed and the extreme importance of wearing eye protection should be emphasized. Many of the toy store chemistry sets have pictures of children on the box doing chemistry but without any kind of eye cover. To initiate the safety discussion, I often run a couple of demonstrations without eye protection and then ask the students what I am doing wrong. From then on, I wear safety glasses.
It is important that the first demonstration be an attention grabber. If methane is available, a good beginning demonstration is to make bubbles with methane and then to ignite them with a barbecue lighter in a darkened room. The same demonstration with air bubbles can be used as the basis of a discussion of the differences in behavior of the two sets of bubbles (density and combustibility).
If liquid nitrogen is available, the presentation can be started out by stating that a mysterious substance in the vacuum flask will be used for several experiments during the course of the presentation (about one every 10 minutes). The students are asked to remember their observations and hopefully deduce the properties (is it hot, room temperature, or cold, is it solid, liquid or gas, is it colored or colorless) and the name of the substance by the end of the program. For the first experiment, a balloon is inflated using the gas from the boiling nitrogen. Other experiments whenever interest seems to be diminishing include:
the shrinking of a sealed inflated balloon - if this is done slowly pausing before actually inserting the balloon in a beaker of liquid nitrogen, some students will predict an incorrect result by covering their ears. (For older students, have them calculate the approximate volume of the balloon that should result for the balloon in liquid nitrogen assuming it is changing from 300 K to 75 K with the effects of the rubber being ignored. The balloon actually will approach a volume of zero and the students should be asked why their calculations are apparently incorrect. If they are allowed to look very closely at the cooled balloon, they should notice the liquid inside.)
the shooting of a rubber stopper out of a plastic bottle into the audience (one student wrote: "And if I ever shot the top off a bottle my Mom would kill me.")
the preparation of a fountain by inserting another rubber stopper in a plastic bottle, this one having a glass tube that extends to near the bottom of the bottle
the freezing and shattering of a flower or in our case a marshmallow - we use marshmallows because they are always readily available
the pouring of the liquid for a very short period on the back of your hand and the throwing of some of the liquid on to a carpeted floor
After seeing the marshmallow, students will respond with great enthusiasm if you ask them if they want you to put your hand in the liquid nitrogen and bang it on the table (don't do it but as indicated above you can pour a small amount carefully onto the back of your hand). One student wrote: "Next time you make an icemallow, taste it and tell me what it tastes like. But if it's poisonis and you die don't tell me. If you ever shater your hand in liquid nitrogen, I hope you have some glue with you." Students have a difficult time grasping the liquid air concept as they do not generally understand the solid, liquid and gaseous states. The system can be related to ice, water and steam but difficulty is still encountered. The teachers should probably discuss the liquid nitrogen demonstration in detail in their classrooms.
Another possible beginning experiment is to spray a prepared sign that says "Welcome" or "Hello" followed by the name of the school. Soon after the first experiment, we start a couple of experiments that take several minutes to reach a discussion stage. A paper chromatogram is started and the students are told that it will be discussed later. After the chromatogram is complete, a discussion is started that focuses on the result and concepts of purity and mixtures rather than on the chromatographic process. In other words, ask the students how the manufacturer makes black ink and then how the chromatography has affected the ink. The answers often include the term "unmix" and the word "separate" is hard to draw out.
A modified blue bottle experiment should also be started early and recycled several times before it is discussed. The solutions are mixed and after several minutes the dextrose in the presence of base reduces the two dyes to colorless forms but swirling introduces enough oxygen to reproduce the colored forms. Usually after the solution loses its color, I ask students to describe their observations. Most will say that the solution has changed from blue to red to clear. Then I ask for the color of water and the point is made that clear does not necessarily mean colorless and that it is very important to be sure that observations are complete and understandable. Actually there is an additional observation that there is some color near the top surface but unless you ask some students near the front to look very carefully at the top surface, most will not see the slight tinge of color and those that do tend to ignore this extremely important clue. After the colored, colorless cycle has been repeated about three times, ask the students to suggest an explanation for the change that occurs upon swirling. Usually the answers include the words "mixing" or "energy" but occasionally without leading too much (ask what you could be adding), someone will suggest air or even oxygen. At this point, you might want to discuss the components of air and most students will say oxygen carbon dioxide and rarely nitrogen. I often get their attention before giving them the top three gases in dry air by telling them they should bet (no more than $1) their parents that they can not name the top three gases. If you want to play a little more with this, after naming nitrogen (78%) and oxygen (21%) and asking how much of a third gas can be present, I write the following on the board and ask them what it is:
If they answer "the alphabet", remind them again of the importance of careful and complete observations. In the sequence of letters the R is missing or the R is gone hence the sequence represents argon or the third most abundant gas in the atmosphere (0.93%) (I recognize that some of you are hissing at this point but that is the expected and desired reaction - humor even if it is kind of primitive is occasionally needed - for more chemistry puns, see http://murov.info/chemicalpuns.pptx or http://murov.info/PPTPreshows.htm ). If the audience will stand for more discussion at this time, it is possible to point out that one of the common answers, carbon dioxide is the fourth gas but at a much smaller amount (0.03%) and the small percentage is the reason that humanity has been able to actually increase its value during the last 50 years by about 25%. This could lead to a discussion of the Greenhouse effect and the possible crisis that could confront society if the dire predictions turn out to be factual.
For performances on campus and sometimes off campus (light, portable vacuum pumps are available), we use a vacuum pump to evacuate a plastic bell jar that contains a marshmallow (or several marshmallows or marshmallow chickens or rabbits) and a slightly inflated tied off balloon taped to the top. The marshmallows and the balloons expand for the same reason although the marshmallows reach a maximum and then shrink back a slight amount presumably due to the popping of some of its cells. If set up correctly, the balloon will eventually break. I then ask for a significant observation and very few report that the balloon made very little sound when it exploded. Again emphasize the importance of complete reporting of all observations. This observation can also be made with a wind up alarm clock or some other sound generating apparatus that doesn't require a wire. A discussion of light and sound waves can follow along with a comparison of their properties (does light need air to travel in?).
Almost any kind of simple observation can be turned into a significant discussion. The simple experiment that follows is good because students can do it at home (They can also do chromatography at home and sometimes I provide a couple pieces of chromatography to each student.). A small heater-stirrer unit is used to heat a beaker of water during the set up procedure. Before the hot water is used for the experiment the children are asked to explain the stirring mechanism of the stirrer. Although it is carefully explained that the heating and stirring mechanisms are independent, someone will answer that the stirring is caused by the heating. Others will say vibration and still others, before the word magnet comes out, will say the white stirrer is a piece of chalk (but would chalk go around?). The reason for the plastic coating on the magnet can also be discussed and some students say it is there to trick them. One fifth grader even came up with an innovative application for the stirrer: "I liked the jar where you make a whirlpool. I wish I had one of them. My dad would mix Martinis with it." It is also possible to bring some chemical engineering into this by asking what properties the white plastic should have and can they think of a plastic with the desired properties.
Now the students are asked to predict and subsequently explain their observations when a drop of food coloring is added to two beakers containing room temperature and hot water respectively. Discussion of the experiment centers around molecules and molecular size and motion. Models of molecules such as water, butane, aspirin, penicillin G, and ampicillin ( a very brief discussion of pharmacology can be brought in here with regard to the differences between penicillin and ampicillin and why chemists designed and synthesized ampicillin) are demonstrated. As a hint on the identification of aspirin, ask the students if they are always good at school or if they ever give their teachers headaches. Interesting answers are obtained if students are asked to compare the number of molecules of water in the beaker to the number in a balloon and to estimate the absolute number. Numbers given will usually be very low (sometimes starting at 3) until you keep telling them "higher". Be prepared to explain the meaning of googol and infinity. Solids, liquids, gases and molecular motion are also compared at this point.
The importance of the use of all the senses (except taste) can be stressed when the solids barium hydroxide octahydrate and ammonium thiocyanate are mixed. This endothermic reaction produces Ba2+, SCN-, water and ammonia. Sometimes, I ask the students to close their eyes before I mix the chemicals and tell me what they think has happened just from the change in the swirling sounds. Students will quickly pick up the solid-to-liquid phase change and if you allow them a quick whiff, some will recognize the smell of ammonia. One student had some interesting spelling in the following comment: "Espally I liked when he truned some stuff into pneumonia." Note the correct spelling of the incorrect concept.
Returning the to observations, most will not report the formation of frost on the exterior of the flask and about half say they think that the flask is hot (many associate chemical reactions with heat evolution). One can let them touch the outside of the flask, read an inserted thermometer (about -10oC to -15oC), and/or freeze an object to the flask by adding water externally. Discussion can follow on observations, the Celsius temperature scale (let the students invent it if they are not familiar with it), reaction energetics (including entropy if desired for high school groups, melting points and the effects of additives on melting points (why doesn't the material in the flask freeze if it is -15oC?). The salting of roads in the winter and the preparation of ice cream and antifreeze mixtures for cars can be discussed.
Some demonstrators feel they must meet the demand of the audience for a fast exothermic reaction but be aware that some students will go home and try to reproduce any explosions they see. Probably the most common reaction run is the combustion of hydrogen in a balloon with or without oxygen (especially for the latter, tell students to cover their ears). Another possibility is the commercially available calcium carbide cannon. A simple, controlled but disgusting example is to drop some glycerol on a small pile of pulverized KMnO4. This should only be done in a ventilated area. Students have commented on this one: I enjoyed all of the experiments except for the one that blew up. Boy it stunk." On the other hand, most feelings are reflected by: "The part that I liked the best was the kind that you do not like."
The combustion of ammonium dichromate can also be performed but it results in the messy production of a hazardous substance. Another exothermic reaction, preparation and combustion of sterno, can be performed and used as an example of a relevant reaction.
The clock reaction can be used in several ways. For sophisticated groups one can ask for predictions about times for diluted systems. The undiluted system as presented takes about 13 seconds for the purple flash of the iodine starch complex. Two-fold dilution with water leads to about a 55 second period. Another variation is to use boiling water to dilute the mixture. The discussion can be related to the ink in cold and hot water experiment. With fifth grade audiences, I ask the classes if they have ever wanted to make noise at school and after their enthusiastic response immediately qualify the comment to say that they all can count as loudly as they want but slowly and in unison. Then I predict that the reaction will take 13 seconds and tell them to start counting at the instant of mixing. Usually if the counting is slow, the solution will turn within a couple of counts of 13.
The oscillating clock reaction (after mixing the color changes colorless to yellow to purple will reoccur many times over a several minute time period) naturally follows the clock reaction and is used mainly for its fascinating properties but it is also used as the basis of a brief discussion on the infancy of scientific discovery and how much there is still left to be investigated. Many children think scientists know everything. The point apparently gets across as students have written: "I know you guys don't know everything" and "I hope you find out about the ones you don't know." The word magic can also be discussed here.
It is important to make the point that chemistry is much more than a series of fascinating demonstrations. Ask the students if they can name any chemicals that they use that were made by chemists. The students have a difficult time answering the question and usually answer with chemicals related to make-up. After some coaching, they are able to realize that they are very dependent in their lives on the products of chemistry. At this point, I synthesize nylon and ask the students to identify it. Answers range from rubber or glue to emission from a sneeze and eventually to cotton and finally to nylon. With regard to cotton, I usually ask them where cotton comes from and whether I could pull it out of a watch glass. Still sometimes the point is hard to make as one student wrote "I didn't know you could make noodles out of those chemicals."
At some point late in the show, the room is darkened and chemiluminescent reaction is performed. This can be related to the earlier energy discussion and with phenomena in nature such as fireflies. With the lights still out the mercury shadowgraph experiment can be run along with a fluorescence and/or phosphorescence demonstration. With the lights back on, a discussion of fluorescence, phosphorescence, spectroscopy, light sticks, evaporation, vapor pressure and the environmental hazards of mercury can follow. Another experiment that can be done in the dark is the electrified pickle experiment. This experiment unfortunately does cause a nasty burning smell and should not be performed long. This demonstration can be related to electrons, electricity and the use of spectroscopy to identify elements (e.g., in stars). Caution the audience that they should definitely not try to reproduce this experiment at home.
Be sure to ask for the answers to the questions about the liquid nitrogen demonstrations before finishing. The sequence of these demonstrations can obviously be altered to suit the needs and style of the presenter. Depending on the number of demonstrations and the length of the discussion, the presentation can be performed in 20 to 90 minutes. Many other suitable demonstration are available in the books given in the earlier web site.
The students who observe the presentation for a second time are usually very quick with the answers to our questions. Because of this, we assume that the educational emphasis of this presentation is worthwhile. And as far a cultivating scientific interest students have written: "Science must be grrrrrreeeeeeaaaaat!" and "And maybe instead of being a football star, I'll be a science professor."
Methane Bubbles. Methane from a natural gas line or a lecture cylinder is connected via a piece of rubber tubing to a very small funnel. After a slow flow is started, the funnel is put into a petri dish containing bubble solution. This takes practice but it is possible to produce bubbles which when shaken free of the funnel rise into the air. The bubbles are ignited with a Bunsen burner or a barbecue lighter. The same experiment is repeated with air if it is available. The burning bubbles are most dramatic in a darkened room. Be sure to have a fire extinguisher handy when you do this experiment and be careful not to ignite the methane anywhere but at the bubbles.
1. A balloon is attached to a piece of vacuum hose with a hose clamp. The other end of the hose is connected to a plastic bottle containing a small amount of liquid nitrogen.
2. An inflated sealed balloon is slowly pushed into liquid nitrogen. Balloons that have bulges or twists are preferred. After the balloon has shrunk to a minimal size, it is allowed to warm to room temperature. If a helium filled balloon is used and the balloon is released in the liquid nitrogen, it will eventually warm up and float to the ceiling.
3. After liquid nitrogen is added to a plastic bottle, a rubber stopper is securely inserted into the bottle. After several seconds it will shoot out into the audience if aimed properly.
4. Into the plastic bottle containing liquid nitrogen, insert a rubber stopper with a 25 cm long piece of 7 mm tubing that reaches to the bottom of the bottle. A fountain will quickly result and if sufficient nitrogen is used, it is possible to almost disappear in the descending fog. The rubber stopper should be held in carefully as on rare occasions, liquid nitrogen runs down the glass tube and can freeze your hand.
5. A marshmallow is placed on a copper wire and inserted into liquid nitrogen. After about 3 minutes, gentle tapping in a beaker will shatter the marshmallow.
6. Liquid nitrogen can be harmlessly poured quickly on the back of your hand for very short periods of time.
7. Have the children separate if the floor is carpeted and leave a wide aisle and throw some liquid nitrogen onto the floor between them.
Welcome School Sign. A 5% aqueous potassium ferrocyanide solution is used to write "Welcome" and a 5% aqueous potassium thiocyanate is use to write the name of the school. The sign is sprayed using a pump sprayer with a 1% aqueous solution of iron(III) chloride.
Paper chromatography. Felt tip pens are used to spot a piece of Whatman #1 chromatography paper cut appropriately (11 x 19.5 cm) to fit a 600 mL beaker. The paper is suspended with a large paper clip on a pencil. When water is used as the solvent, the separation is not complete but sufficient for students to see separation and differences between different colors and the same color of different brands. About 40 mL of a 1:1:1 mixture of 1-butanol, ethanol and 2 M ammonia works much better with some brands and the mixture seems to be stable for long periods of time. It does require more time for preparation and it smells.
Vacuum Experiments. Plastic bell jars and portable vacuum pumps are available form commercial lab supply companies. The latter are rather expensive and a relatively good one is needed to pop the balloon. Around Easter, it is advisable to stock up on marshmallow chickens and rabbits.
Molecular Motion. A drop food coloring is added to tall 200 maL beakers containing room temperature and very hot water. The heater stirrer unit should be one that heats rapidly and does not have the word magnetic printed on the front.
Endothermic Reaction. Vials containing 20 g of Ba(OH)28H2O and 10 g of NH4SCN (other chemicals can be substituted such as Sr(OH)28H2O and/or NH4Cl but the reaction is not quite as dramatic). The formation of water and frost can be observed and the presence of ammonia detected by smell. The flask gets cold enough (-20oC) to condense moisture form the air. The condensation can be demonstrated by rubbing some of the frost with a finger. Some students near the front can be allowed to touch the flask and tell the other students that it is cold. Some students assume all chemical reactions evolve heat and confuse the frost with steam. The flask gets cold enough to freeze water added to the bottom of the flask and the flask can be frozen to a smooth surface using ice as glue.
Blue Bottle Experiment. The following four solutions are prepared and stored in plastic bottles and dropper bottles.
Solution A: 32 g KOH/500 mL water
Solution B: 40 g dextrose/500 mL water
Solution C: 0.04 g methylene blue/100 mL water
Solution D: 1 g resaurzin (tablet form)/100 mL water
Mix about 30 mL of solution A, 30 mL of solution B, 10 drops of solution C and 10 drops of solution D. Stir, allow to sit and turn pink and then almost colorless (several minutes the first time and shorter amounts of time later depending on the amount of stirring). Pick up the flask very carefully and give it one quick swirl to turn it pink. Continued stirring will turn the solution purple. The cycle can be repeated many times.
Exothermic Reaction. Fill a vial with KMnO4 that has been ground up with a mortar and pestle. Place about a pop bottle cap full in a Pyrex Petri dish and add a few drops of glycerol to the KMnO4. After several seconds, the mixture will start to smoke, crackle and eventually ignite. Unfortunately, the reaction also give off a nasty smell.
Canned Heat. In a Pyrex Petri dish, put a few mL of saturated aqueous calcium acetate solution (about 35g/100 mL). Add ethanol, mix, and pour off the excess alcohol from the gel formed. Ignite with a match and sprinkle some boric acid on the flame.
Clock Reaction. Prepare the following two solutions in plastic bottles:
Solution A: Dissolve 4 g of soluble starch in 1 L of boiling water. After cooling, add 2 g of Na2S2O5.
Mix: 25 mL of solution A and 25 mL of solution B (about 13
seconds for color change)
Mix: 25 mL of solution A and 50 mL of water and then add 25 mL of solution B (about 55 sec.)
Mix: 25 mL of solution A and 50 mL of very hot water and then add 25 mL of solution B (about 30 seconds)
To turn this reaction into the Old Nassau (Halloween) reaction, add
10 mL of a mercuric chloride
(0.15 g HgCl2 per 100 mL H2O) to a flask followed by 25 mL each of A and B. After about 0.5 minutes,
the solution will turn orange and another 0.5 minutes later, dark purple. Be aware of the disposal hazards
of mercury(II) ion.
Oscillating Clock Reaction. Prepare the following solutions in plastic bottles:
Solution A: Dilute 206 mL of 30% H2O2 to 500 mL with water. [Note: Walter Rohr informs me that 27%hydrogen peroxide can be purchased under the trade name Baquacil Shock and Oxidizer from pool stores. Check with http://www.baquacil.com/ for location of stores.]
Mix: Equal volumes (for small audiences, 25 mL of each is sufficient) of solutions A, B, C in an Erlenmeyer flask. While the demonstration is dramatic in an Erlenmeyer flask, it is even more impressive if the solution is quickly transferred to a graduated cylinder as there is a spatial effect to the oscillations easily observable.
Nylon. In a glass bottle, prepare a 0.25 M adipyl chloride solution in cyclohexane. Transfer about 20 mL of this solution to a plastic dropper bottle. In a plastic bottle, prepare an aqueous solution containing 0.5 M 1,6-diaminohexane and 0.5 M NaOH. Put about 2 mL of the amine solution in a shallow dish or watch glass and while adding the acid chloride solution dropwise, slowly pull out the nylon with a looped copper wire.
Chemilumescence. Prepare the following solutions in plastic bottles:
Solution A: Dissolve 2 g of luminol (aminophthalhydrazide) and 2.5 g of
NaOH in 1 L of water.
Solution B: 0.15% H2O2
Mix: 40 mL each of solutions A and B in a graduated cylinder. Sprinkle a few crystals of K3Fe(CN)6 into the cylinder for an interesting effect and then add a larger quantity for maximum light output. For a yellow emission, add after the blue emission is observed, a few drops of a solution of 1 g of fluorescein and 1 g NaOH in 100 mL of water.
Mercury shadowgraph. Fluorescence is demonstrated first using a precoated thin layer chromatography sheet with a fluorescent indicator. A short wave (254 nm) mineral is a convenient portable light source. Next, a shallow plastic bottle of mercury opened and placed between the light and the fluorescent screen. In a sufficiently darkened room, the shadows of the mercury vapor are easily observed on the screen. A little blowing on the mercury sometimes enhances the demonstration.
Fluorescence and Phosphorescence. Fluorescence can be conveniently demonstrated by writing on Whatman No. 1 filter paper with solutions containing 0.02% methanol solutions of Rhodamine B (caution - suspected carcinogen), fluorescein, or acridine orange. For phosphorescence, write on the filter paper with a 5x10-3 M solution of a polynuclear aromatic acid ( e.g., naphthoic acid, naphthalene sulfonic acid) in a 1 M NaOH solution. 2-Naphthol gives both fluorescence and phosphorescence under these conditions. After drying irradiate with the 254 nm line of a mineral light in a dark room.
Electric Pickle. This experiment should be performed in a well ventilated area or for a very short time only. Cut off the female end of an inexpensive cord and split the wires. Solder large sheet metal screws to each of the wires. Support a large dill pickle in some way that won't require touching (we use a ring stand and a clamp) and insert the sheet metal screws into opposite ends of the pickle. Plug the cord directly into a socket and after several seconds smoke should start coming out of the pickle and shortly thereafter, it should start glowing. At this point, the lights should be turned out but remember to run this for a short period of time and be very careful not to electrocute yourself. Students should definitely be cautioned not to try this one at home. There have been several articles in the Journal of Chemical Education on this reaction in the mid 1990's.
FLASHING, AND GLOPPPING TO HOLIDAY MUSIC Steven Murov, Modesto Junior College, firstname.lastname@example.org
Chemistry presentations at the beginning of the winter holiday season are becoming a common, wonderful tradition (1). After giving an educational chemistry presentation entitled "Flash, Wobble and Glop" (2) several hundred times, I decided to jump on the bandwagon and seek stardom for one night by attempting to present an edutaining (strong emphasis on entertainment) chemistry presentation to a family type audience in an auditorium that seats close to 1000 people. The challenges are many and different than those confronted when giving educational demonstrations to audiences of elementary school students of about 100 people. First there must be a continuous flow with minimal time periods between demonstrations. Second, as an audience in excess of 500 was expected and realized, the demonstrations had to be selected for visibility at some distance. Large scale demonstrations were selected from the fantastic presentations of Weird Science (Chemistry West Group of Illinois - Bob Lewis, D. Lieneman, L. Marek, Bill West), Robert Becker (Kirkwood High School in Kirkwood, MO), Al Guenther (Science Consultant to Beekman's World), and the excellent books of Chen (3) and Summerlin and Ealy (4) and from "Flash, Wobble and Glop" (2). Weird Science solves the flow problem by having three or more presenters who prepare and joke with each other while the another presents. Because of the appropriateness for the holiday season it was decided to have a live band1 accompany the demonstrations with appropriate music and fill in the slow moments. It was decided to call the presenters "Dr. Al Chemist and the Electric Pickle Band."
Despite the primary goal to provide entertainment, the opportunity to devote the first ten minutes to endorse science education with a now captive audience of over 500 people could not be bypassed. First, to impress upon the audience the importance of science literacy both for society and personal reasons, several questions were put on the overhead and the audience was asked to vote on each question. Typically questions like the following are used:
1. Would you allow construction of a nuclear fusion energy facility in your downtown area?
2. Is there a significant relationship between the greenhouse effect and the ozone hole?
3. Is the substance, vitamin C, obtained from natural products different from
vitamin C, obtained from synthetic sources?
After a very brief discussion of these questions, it was pointed out that despite the importance of science in many of our daily decisions, the image of a scientist historically and even currently is a rather negative stereotype. We were somewhat surprised prior to the presentation that many people asked why the scientist in the presentation was titled Dr. Al Chemist. Because of this, one of the classic pictures of an alchemist by David Teniers the Younger (see http://murov.info/alchemists.htm ), was shown and the goal of alchemists was explained. Then a sketch of another alchemist by David Teniers, the Elder2, depicting an ape in a setting very much like the previously mentioned picture was used to show that even around the year, 1650, people mocked "scientists". Interestingly the ape picture is called "Les Plaisirs des Fous" or "The Pleasure of Fools" (for other pictures of alchemists, see http://www.levity.com/alchemy/graphics.html). Unfortunately the comical or even negative image of scientists persists today. We have had 5th grade students draw scientists (we showed some of these pictures to the audience using overheads) and by far the most common drawing is still a stereotypical image of a lone male with little hair or wild hair, glasses, a lab coat, glasses and a pocket saver (again see http://murov.info/alchemists.htm ). Our unrefined results generally agree with studies reported in the literature (5-17).
To complete this attempt to provide an awareness of the importance of science, examples of errors in the media were presented. For instance, a Newsweek photo several years ago that showed a child apparently receiving KI was captioned with "On Alert: Administering iodine to Polish children" (18). On a lighter side, Richard Pryor as the computer scientist in Superman 3 analyzed kryptonite. In addition to its well recognized property that it is lethal to Superman, kryptonite is supposed to be harmless to humans. The analysis revealed the following mixture - 15.078% plutonium, 18.06% tantalum, 27.71% xenon, 24.02% promethium, 10.62% dialium, 3.94% mercury and 0.57% unknown. This is clearly a mixture that would be harmful to humans. The reference to Superman was used primarily to segue into a discussion of the way Clark Kent changes into Superman. At this point, the I walked into a port-a-potty and while the band plays "Big Bad John" and/or "How Dry I Am" I changed into the stereotypical chemist, Dr. Al Chemist in this case. While in the port-a-potty, a flash camera and/or a cap gun was set off.
The remainder of the program was a combination of chemical demonstrations and music selected for adaptability to the holiday theme. The table below is offered as a starting point and as a catalyst for the development of additional demonstrations. The presentation should be adapted to the personalities and styles of the presenters.
DEMONSTRATIONS, INSTRUCTIONS, MUSIC
|Sign||5% potassium ferrocyanide, 5 % potassium thiocyanate, 1% iron chloride, filter paper||"Star Spangled Banner" (have audience sing it)||Write on Whatman #1 filter paper with the first two solutions in advance of show (e.g. Happy Holidays). Spray with iron chloride. If preparation time is not a problem, on Whatman chromatography paper (46 x 57 cm), prepare a U.S. Flag with the thiocyanate as the stripes and the ferrocyanide as the background for the stars. While the audience sings the Star Spangled Banner, have a few people in the audience release rocket balloons when the words "rocket's red glare" are reached. When "bombs bursting" is reached, set off an explosive such as a carbide cannon or a small amount of hydrogen and oxygen. Spray the sign as the audience sings "the flag was still there".|
|Waterlock||Waterlock, salt, water, translucent container||"How Dry I Am"||Add water to translucent container that has Waterlock in it. Turn bottle upside down and nothing comes out. Add salt and stir and aqueous phase is pourable again. Mention diapers to make relevant. An alternative is to play the 3 cup trick with the audience. Put a small amount of waterlock in a cup before the audience enters the room.|
|Methane Bubbles||methane, small funnel, bubble soap or 9 mL Joy + 300 mL water, barbecue lighter||"Deck the Halls with Balls of Fire"||Carefully ignite methane bubbles with lighter. Make sure fire extinguisher is handy. Do in dark room. Note that lecture cylinders of methane are very expensive (over $150). Propane is much cheaper and can be used but the bubbles will go down instead of up.|
|64 g KOH/L water, 80 g dextrose/L water, 0.04% methylene blue solution, 1% resaurzin||Any Blues song||Mix equal amounts of base and sugar solutions and add about equal amounts of dye solutions until solution is very blue. Swirl, and allow to sit until solution turns colorless then swirl again.|
|30 g NaOH/L water, 40 g dextrose/L water, 10 mL 1%indigo carmine, 2 two liter soda bottles, tornado tube connecter.||"Green, Green ..."||Mix equal amounts of base and sugar and add of the dye. Add to 2 liter bottle and connect to other bottle with tornado tube. Tip up-side-down and swirl to start tornado.|
|Plastic Bell Jar, Frosty the Snowman figure made out of marshmallows and toothpicks||"Frosty the
|Evacuate the bell jar with marhmellows (or Peeps) inside. After expansion has maximized, a small amount of contraction will take place. Then quickly let air back into jar. Also suspend a tied off balloon with a small amt of air in it. If it pops, the there will not be much sound and you can talk about the transmission of sound waves. If a 5 gallon can is available, attach the vacuum pump to it. Generally it will collapse in a very dramatic fashion. Another fascinating demo can be run if you find a small plastic pumpkin that fits into the bell jar. Squirt some shaving cream into the pumpkin, insert the pumpkin into the bell jar and evacuate the chamber.|
|Hollowed and carved pumpkin, 400 mL beaker, 150 mL 30% hydrogen peroxide (see oscillating clock below for source), 7 mL Joy, 7 mL 2 M NaI, food coloring||During the show, I did this reaction in a graduated cylinder and the band sang the "Pepsodent Song" but the "Weird Science modification of doing this in a pumpkin produces a much more fascinating albeit gross effect. Mix everything except the NaI in the beaker and place in the pumpkin. Add the NaI and close the pumpkin. It saves some cleanup if the pumpkin is placed on an inverted dishpan with a dishpan in front of the pumpkin.|
|Colored Shadows||Blue, green and red spot lights several feet apart aimed at the same place on a screen. I used 3 overheads with blue, green and red cellophane on the top. Portable screen||Select a couple of volunteers and have them stand near the screen and slowly move their hands to make colored shadows on the screen. Before doing this, ask the audience to tell you what colors shadows are.|
|Phosphor. screen||large poster board or screen painted with phosphorescent paint, flash attachment for camera||Have a volunteer in a dark room jump in front of the screen. Set off the flash at the maximum of the jump. A shadow of the jump will remain on the screen.|
|Vision persistence||6 ft of 3/4 inch PVC pipe, overhead or slide projector, overheads or slides with Santa picture or letters "OIC"||"Here Comes
|Stand where screen would be for overhead and rapidly wave pipe back and forth. Letters or image should be visible to audience.|
|Paper streamers||blower (leaf) or reverse end of vacuum, toilet paper, red and green crepe paper, round stick||"We Wish You a Merry Xmas", "I Am Dreaming of a White Xmas"||Direct the air immediately over the roll of paper on the round stick.|
|A. 30 g iron(III) chloride/100 mL water
B. 22 g ammonium thiocyanate/100 mL water C. 20 g tannic acid/20 mL D. saturated oxalic acid
|Mello Yellow||Flask 1 - 15 drops of A, Flask 2 - 1 drop of B, Flask 3 - 4 drops of B, Flask 4- 12 drops of C, Flask 5 - 10 mL. Start with 1 L beaker with 400 mL water. Pour 100 mL into A, then back into beaker, repeat with each flask.|
|Hula hoop with PVC pipe handle, 4 ft. diameter swimming pool, strong stand in middle of pool, 2 L Joy, 50 mL glycerin, 15 L water||Joy to the World"||Two volunteers are needed from the audience. Put one on the stand in the pool and the other right next to the pool. With practice, it is possible to pull bubble over one and down on the other.|
500 mL water in 1L beaker, green food coloring, 1
"melt-away bag" or 100 mL1% polyvinyl alcohol,
10 mL 4%
|"Great Green Gobs..."||Stir bag vigorously in water. Add food coloring and borax and mix.|
|Clock||12 Erlenmeyer flasks
A. 4 g soluble starch, 2g sodium metabisulfite/ L B. 2 g potassium iodate, 0.3 mL conc sulfuric acid/L
|12 volunteers are given an Erlenmeyer with 50 mL of A. Each volunteer is also given a 100 mL graduated cylinder containing 50 mL of B + 4 mL of water times their number -1(e.g., number 4 has 12 mL water. They are told to mix at the same time about 13 seconds before the number one in the song.|
|A. 3 g soluble starch, 11.7 g malonic acid, 2.5 g
manganese(II) sulfate/750 mL
B. 206 mL 30% hydrogen peroxide/500 mL
C. 21.4 g potassium iodate, 2.2 mL conc. sulfuric acid/500 mL
|"Jingle Bells"||Mix equal amounts of the three solutions in an Erlenmeyer and then pour into a graduated cylinder. Have the audience sing the song and sway from one side to the other with each color change. [Note: Walter Rohr informs me that 27% hydrogen peroxide can be purchased under the trade name Baquacil Shock and Oxidizer from pool stores. Check with http://www.baquacil.com/ for location of stores.]|
|Smoke machine (smoke bombs work but not as well), garbage can with 6 inch hole on closed end and flexible plastic fastened to cover other end||"Smoke Gets in
|Shoot smoke rings out into audience|
Plastic bottle, 1 hole rubber stopper with 25 cm glass tube in it
Snake like balloon. Beaker.
"O Come All Ye
Add about 50 mL to the bottle and insert stopper. A fountain will result. Be careful not the let nitrogen run down on to hand and cause frost bite.
Slowly insert balloon into nitrogen until its volume is close to zero. Withdraw and allow it to resume original size. The song was used because I painted the balloon with phosphorescent paint and turned off the lights but the paint flaked off during the process.
|Sunset||Overhead projector, overhead sunset scene, large crystallizing dish, 400 mL 0.04 M sodium thiosulfate, 40 mL 2 M sulfuric acid||Sunset music||With crystallizing dish on top of sunset scene, add acid to thiosulfate solution and stir.|
|Chemistree||see reference 2||"Oh, Christmas
mini-marshmallows 1 - 2
ft of 1/2 inch pvc
regular Kraft mm - use tube from plastic wrap
|added 12/11/08 adds to many uses of mm - liq. N2, vacuum||Commercial marshmallow blasters are available for about $20 with repetitive capability for minis. However, tubes alone do job for under $1. Plans are available on the Internet for making shooters look more like gun but straight tubes are just as effective.|
1. Gammon, Steven D. and Graduate Students for Chemical Education, J. Chem. Ed. 1994, 71, 1077-1079.
2. Murov, Steven, J. Chem. Ed. 1994, 71, 1082-1083.
3. Chen, P. S., Entertaining and Educational Chemical Demonstrations, Chemical Elements Publishing Co., 1974.
4. Summerlin, L., Ealy, J., Chemical Demonstrations, A Source Book for Teachers, American Chemical Society, 1985.
5. Sherwood, M., New Scientist 1970, 47, 382-384.
6. Jensen, W. B., Chemistry 1971, 44, 6-9.
7. Basalla, G., in Science and Its Public: The Changing Relationship, Holton, G., Blanpied, W. A., Eds., Reidel: Boston, 1976; Vol. 33, 261-278 and references therein.
8. Mead, M., Metraux, R., Science 1975, 126, 384-390.
9. Chambers, D. W., Science Education 1983, 67 (2), 255-265 and references therein.
10. Schickel, R., Discover 1985 (August), 71-756.
11. Sun, M., Science, 1985, 228, 1294.
12. Weart, S., Physics Today 1988 (June), 28-37.
13. Burdick, A., The Sciences, 1992 (Nov./ Dec.), 6-7.
14. Eisenberg, A., Scientific American 1993 (April), 128.
15. Haynes, R. D., From Faust to Strangelove: Representations of the Scientist in Western Literature, Johns Hopkins Univ. Press., Baltimore, 1994.
16. Allen, G. S., The Massachusetts Review 1989+, 505-555.
17. Rahm, J. and Charbonneau, P., Am. J. Phys., 1997 (August), 774-778.
17. Rosenbaum, G. P., Chemistry 1972, 45, 14-18.
18. Newsweek, May 12, 1986.
1The title "Electric Pickle Band" selected for the band was derived from the final demonstration. Its members were Dennis Wazac, Connie Hightman, Gary Hyman, Bob Man.
2The sketch is available at the Cribbs Collection (Royal Society of Chemistry, Burlington House, London WIVOBN) for a fee.
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