CHEMISTRY DEMONSTRATIONS (#2):
This web site was split on 1/30/21 into two
websites, this page (http://murov.info/chemdemos2.htm) and the original site: http://murov.info/chemdemos.htm.
This site includes a different narrative and emphasizes the American flag demo.
A PowerPoint program has been designed to be used with the flag demo and is available at:
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:
Safety in Chemical Demonstrations
http://www.chymist.com/Safety with chemical demonstrations.html
Audience Participation Chemistry Demonstrations Including the American Flag Demo
Chemistry demonstrations that illustrate the importance and excitement of science should stimulate interest in science and have a positive impact on the science literacy of the audiences. To increase audience attention and learning and to dispel the aura of “magic” that sometimes accompanies chemistry presentations, it is beneficial to involve the audience in interactive ways during the show. Methods of including audience participation are discussed for several demonstrations with the emphasis on the preparation of an American flag while the audience sings the National Anthem.
Audience Participation Chemistry Demonstrations Including the American Flag Demo
Chemistry presentations for K-12 students and general audiences that illustrate the importanceand excitement of science should stimulate interest in science and have a positive impact on the scienceliteracy of the audiences (1-15). To increase audience attention and learning and to dispel the aura of“magic” that sometimes accompanies chemistry presentations, it is beneficial to involve the audience in interactive ways during the show. Methods of including audience participation are discussed for several demonstrations with the emphasis on the preparation of an American flag while the audience sings the National Anthem. http://murov.info/NationalAnthem(U.S.).ppt Instructions follow in the supplement below.
Public events often begin with the singing of the National Anthem. This tradition is appropriate for the opening of a chemistry show. The words to the National Anthem are projected using a computer or an overhead transparency. Another option is to use or develop a PowerPoint presentation that illustrates the Anthem line by line (16). Shortly before the beginning of the show, a few people are selected from the audience and each is given a rocket balloon and an air pump. The audience is asked to stand and at the count of 3 to sing the Anthem. As the audience starts singing, the “rocket people” should fully inflate their balloons and hold onto them. When the singing reaches rockets red glare, the balloon holders should release the balloons aimed up and toward the back of the audience. When the singing reaches bombs bursting, the presenter should explode a carbide cannon (17) or another safe type of explosive. Finally, when the singing reaches the flag was still there, the presenter should spray aqueous FeCl3 on a flag previously prepared with aqueous KSCN stripes and aqueous K4Fe(CN)6 background for the stars (18-20). Details for preparation of the flag and possible alternative chemicals such as the use of acid base indicators are included in the supplementary online material. The flag demonstration can be used as a teaching moment to emphasize the importance of observation in science. After singing the Anthem, the audience can be asked if the Anthem has ever led to the questioning of any of the contents of the Anthem such as the meaning of the word ramparts. Despite the fact that the audience has heard or sung the Anthem dozens of times, most people have overlooked the fact that they don’t know the meaning of ramparts and could want to improve their observational skills. A picture that illustrates the National Anthem and contains ramparts is available online (21). It is interesting to ask and discuss what was meant by rockets red glare when the song was published in 1814. The audience can also be asked how many are aware that there are several more verses to the Anthem. At the risk of starting a political debate, the audience can be asked if it is appropriate for the Anthem to focus on war instead of peace or the beauty of our country (e.g., see the 03/02/09 Get Fuzzy comic strip by Darby Conley). Finally, some humor can be added by informing the audience that a critique of their singing is in vogue. This can be followed by showing a picture of American Idol’s Simon Cowell (22).
Other demonstrations that are nicely suited for audience participation
include the clock, oscillating clock, a modified blue bottle, nylon, sodium
polyacrylate, vacuum and pressure and liquid
nitrogen experiments. For the clock reaction, it has been suggested that many solutions be prepared to change color at climactic moments in the William Tell Overture (another option is the 1812 Overture) (23). The preparation for this is time consuming and the demo is difficult to time properly. A simple alternative is to tell the audience to count slowly, loudly and in unison when two solutions are mixed. Before mixing, predict the number on which the change will occur but point out there is a considerable margin of error. For the oscillating clock, in advance, tell the audience to lean collectively to the right and say ooh when the solution turns dark blue. When the solution turns colorless, they should lean to the left and say aah. They can relax and sit straight up when it is briefly yellow. Be sure to let the audience know when they can stop reacting to the demonstration.
A valuable lesson can be taught with the use a modified blue bottle experiment (contains methylene blue, resaurzin, sodium hydroxide and glucose) (24). This reaction should be started early in the program with the alert that the audience should glance at it occasionally. After it turns colorless (except for an important tinge of color on the top surface that the audience will not be able to observe), one swirl should turn it red and vigorous stirring turns it blue. The standing, stirring cycles can be repeated periodically until you are ready to discuss the reaction. Most audiences when asked why the red and blue appear with mixing usually respond that the stirring adds energy or that the color at the top is just being mixed around. Usually it takes the hint that a substance is being added as a result of stirring to lead people to suggest that the color change is due to air. It is now appropriate to ask what the three most abundant gases in dry air are. Few people seem to know that nitrogen is number one and it is very rare that anyone knows that argon is number 3. If you want to introduce a pun, write ABCDEFGHIJKLMNOPQSTUVWXYZ on a board and tell the audience that the letters represent the third most abundant gas in dry air. If someone responds “the alphabet”, remind the audience of the importance of complete, careful and unbiased observations. Someone will usually then say that the R is missing which then slowly but surely leads to the recognition that argon is the third most abundant gas. Even more important, usually someone will say that carbon dioxide is one of the top three and some people think it is number one. This is another great teaching moment as you can point out that carbon dioxide is number 4 but currently makes up only 0.038% of the atmosphere. Because there is not much present, human activities have caused a 36% increase in the carbon dioxide content and it will continue to increase and arguably stress global climates unless society quickly find alternates to fossil fuel consumption.
Nylon synthesis and the use of sodium polyacrylate (diaper powder) are
good ways to lead in to a discussion of the importance of chemistry.
Elementary school students when asked if they use human-made chemicals usually only name cosmetic products. The
students have just never thought about or been asked to think about the
source of products such as medicines, plastics and synthetic fabrics. Many
other demonstrations can be used to initiate meaningful discussions with an
audience. Vacuum demonstrations including expanding marshmallows and balloons
and collapsing containers (when evacuated) can be used to discuss pressure
and the nature of sound and light waves. If liquid nitrogen is available,
tell the audience you are going to do several experiments with a
mysterious substance and ask the audience to be good observers of the
experiments. Tell them you will ask them several questions at the end of the
a. What color is the substance? Sometime during the presentation, ask the audience the color of water and point out why clear, transparent or white are either not answers to the question or incorrect. This does raise the question whether the terminology “white wine” is appropriate.
b. Is it hot, room temperature or cold?
c. Is it a solid, liquid or gas?
d. What is the substance?
Once the attention of the audience has been attained, the opportunity to discuss the importance of science literacy should not be passed up. Ask the audience how they would vote on possible construction of a nuclear fusion energy facility in their community. Most people react to the word nuclear and do not know the difference between fusion and fission. Show pictures drawn by students that depict scientists as mad (almost all pictures show a lone crazy looking white male scientist with either no hair or very strange hair) (25-29). Use the nylon, liquid nitrogen and other demonstrations to point out the importance of science and discuss the very misguided stereotype of a scientist. A scientifically literate society is needed if we are going to make the best decisions in the future and you will be rewarded with the audience reaction to your presentation.
1. Louters, L. L.; Huisman, R. D., J. Chem. Ed.,1999, 76, 196.
2. O'Brien, T., J. Chem. Ed., 1991, 68, 933.
3. Sullivan, D. M., J. Chem. Ed., 1990, 67, 887.
4. Fenster, A. E.; Harpp, D. N.; Schwarcz, J. A., J. Chem. Ed., 1985, 62, 1100.
5. Waterman, E. L.; Bilsing, L. M., J. Chem. Ed., 1983, 60, 415.
6. Bergmeier, B. D.; Saunders, S. R., J. Chem. Ed., 1982, 59, 529.
7. Katz, D., J. Chem. Ed., 1991, 68, 235.
8. Wolfe, R., J. Chem. Ed., 1990, 67, 1008.
9. Stamm, D. M.; Franz, D. A., J. Chem. Ed., 1992, 69, 762.
10. Ihde, J., J. Chem. Ed., 1990, 67, 264.
11. Wright, S. W.; Cotton, W. D.; Hess, V. G., J. Chem. Ed., 2002, 79, 44.
12. McRae, R.; Rahn, J. A.; Beamer, T. W.; LeBret, N., J. Chem. Ed., 2002, 79, 1220.
13. Meyer, L. S.; Schmidt, S.; Nozawa, F.; Panee, D. J. Chem. Ed., 2003, 80, 431.
14. Roadruck, M. D., J. Chem. Ed., 1993, 70, 1025.
15. Ophardt, C. E.; Applebee, M. S.; Losey, E. N., J. Chem. Ed., 2005, 82, 1174.
16. Murov, S., http://murov.info/NationalAnthem(U.S.).ppt or an older version at http://www.slideshare.net/murovs/national-anthem-3064731
17. Conestoga Company’s Big Bang Cannon, http://www.bigbangcannons.com/ .
18. Chen, P. S., Entertaining and Educational Chemical Demonstrations, Chemical Elements Publishing
Co., 1974, 20.
19. Reising, J. M.; Nguyen, P. N.; Flint, E. B.; Campbell, D. J., Chem. Educator, 2007, 12, 85-88.
20. Old Glory: A Patriotic Colors Demonstration, http://www.flinnsci.com/media/395499/cf0438.00.pdf
21. Battle for Fort McHenry,
22. For example, see: http://i1.cdnds.net/13/41/618x426/simon-cowell-1.jpg
23. Brice, L. K., J. Chem. Ed., 1980, 57, 152
24. Chen, P. S., Entertaining and Educational Chemical Demonstrations, Chemical Elements Publishing
Co., 1974, 38.
25. Sjoberg, S., Science And Scientists: The SAS-study, http://folk.uio.no/sveinsj/SASweb.htm (accessed
26. Google "Matkins Drawing a Scientist."
27. Science and Technology: Public Attitudes and Public Understanding,
http://www.nsf.gov/statistics/seind02/c7/c7s3.htm (accessed 03/02/09).
28. Nuno, J., Draw a Scientist: Middle School and High School Students’ Conceptions about Scientists,
http://www.jdenuno.com/Resume%20Web/DAST.htm (accessed 03/02/09).
29. Murov, S., Pictures of Alchemists by the David Teniers,
http://murov.info/alchemists.htm (accessed 03/05/09).
Audience Participation Chemistry Demonstrations: Online Supplement
American flag.1 General findings included the following: For paper, Whatman #1 Chromatography paper costs more than other absorbent paper at about $2/sheet (46 cm x 57 cm sheet which can be cut into four 8.5 inch x 11 inch sheets) but a less expensive alternative is available from Sargent-Welch at https://www.sargentwelch.com/store/catalog/product.jsp?product_id=8869823 . Watercolor and construction papers were easier to paint along lines but spraying usually resulted in running of most of the colors. The red from 5% aqueous KSCN + 2% aqueous FeCl3 spray ran the most but acid base indicators phenolphthalein and thymolphthalein + 0.1 M NaOH spray also ran. Only the blue from 5% aqueous K4Fe(CN)6 appeared to bind to the watercolor and construction papers and not run. For large audiences, use of the whole 46 cm x 57 cm sheet is desirable for adequate visibility but requires much more preparation time than use of an 8.5 inch x 11 inch sheet (adequate for audiences of 100 or less). The large sheet requires pencil lining by hand using template 1 and substantial painting time while the 8.5 inch x 11 inch sheet can be lined with a printer using the template below and painting time is relatively short. Alternatives for colors include 5% aqueous KSCN for red and 5% aqueous K4Fe(CN)6 for blue with spraying with 2% aqueous FeCl3 or 0.5% phenolphthalein in 95% ethanol for “red” (quotation marks because the red is reddish-pink) and 0.5% thymolphthalein in 95% ethanol for blue with spraying with 0.1 M NaOH. The acid-base indicators have the disadvantage that 0.1 M NaOH is caustic and must be sprayed very carefully away from any people. In addition, the blue lasts only a few minutes before fading (presumably due to carbon dioxide in the air). The fading could be used in conjunction with the blue bottle experiment to discuss the issue of carbon dioxide and global climate change but has the disadvantage that the fading of the blue contradicts the “flag was still there” theme of the National Anthem. The K4Fe(CN)6 has the disadvantage that yellow, tarts to appear about a week after painting so painting should be performed within a few days of use.
For multiple copies of flags, use pencil on a piece of Whatman 46 cm x 57 cm Chromatography paper or less expensive Sargent Welch paper https://www.sargentwelch.com/store/catalog/product.jsp?product_id=8869823 to draw the lines as indicated in Template 1 to make a large flag. Technically, the paper does not have the correct length to width ratio for an American flag2 but it is easier to use the paper as it comes from the box. If you choose to cut it to the proper ratio of dimensions, then all measurements will need to be recalculated. Use Template 1 to mark one flag and use that marked flag as the template for all future flags. Tape the flag to a piece of cardboard or mat board before applying the solutions. Painting should be done at least a couple of hours before use to allow for drying. Use about a 3/4 inch brush to paint the stripes with 5% aqueous potassium thiocyanate solution (or 0.5% phenolphthalein in 95% ethanol). Because the solution will spread about 1/8 inch in both vertical directions, some space should be left between the application and the pencil lines. For the star portion of the flag, use a small brush (about 1/4 nch) and paint a frame with 5% aqueous potassium ferrocyanide (or 0.5% thymolphthalein in 95% ethanol) around the star section. Now paint diagonally in both directions between the pencil lines leaving intersections of the pencil lines dry. There also might be a few spots around the edges that need to be filled in with the potassium ferrocyanide solution. Only one student out of hundreds has ever complained that the stars that result are distorted circles rather than stars. After the paper is dry, use a spray bottle to apply 2% aqueous iron(III) chloride (or 0.1 M NaOH). The words to the National Anthem are available online.
For smaller flags, cut the 46 cm x 57 cm sheet Whatman paper into 8.5
inch x 11 inch pieces and run them through a printer capable of dealing with
relatively thick paper using template 2 or 3. Paint as above. For the star
portion, paint around the region and then diagonally between the stars making
no attempt to make actual stars.3
Clock Reaction. Prepare the following
two solutions in plastic botles:
Solution A: Dissolve 4 g of soluble starch in 1 L of boiling water. After cooling, add 2 g of Na2S2O5.
Solution B: Dissolve 2 g KIO3 in 1 L of water containing 0.3 mL of concentrated sulfuric acid.
Mix: 25 mL of solution A and 25 mL of solution B (about 13 seconds for color change)
Oscillating Clock Reaction. Prepare the following solutions in plastic bottles:
Solution A: Dilute 206 mL of 30% H2O2 to 500 mL with water. [Note: 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.]
Solution B: Dissolve 21.4 g of KIO3 in 500 mL of water containing 2.2 mL of 18 M H2SO4.
Solution C: Dissolve 3 g of soluble starch in 750 mL of boiling water. To the cooled solution, add 11.7 g of malonic acid and 2.5 g of MnSO4 . H2O.
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 after mixing to a graduated cylinder as there is a spatial effect to the oscillations that is easily observable.
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. Vigorous stirring will turn the solution purple. The cycle can be repeated many times.
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 of copper wire with a small loop at its end.
Sodium polyacrylate. Add water to translucent container that has sodium polyacrylate in it. Turn bottle upside down and nothing comes out. Add salt and stir and the aqueous phase can be poured again. Mention the role of the powder in disposable diapers to make the discussion relevant. An alternative is to play the 3 cup trick with the audience. Put a small amount of sodium polyacrylate in a cup before the audience enters the room. Vacuum and pressure. Evacuate a bell jar with marshmallows (or Peeps) inside. After expansion has maximized, a small amount of contraction will take place. Then let air quickly reenter the jar. Also suspend a tied off balloon with a small amount of air in the bell jar. If it pops, the there will not be much sound and you can talk about the transmission of sound waves. Attach the vacuum pump via a hose connected to the appropriate size single hole rubber stopper to a large plastic bottle and afterwards to a 5 gallon metal can (empty acetone cans that have been thoroughly rinsed with water usually work). Generally, collapse occurs in a very dramatic fashion.
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 more interesting. After the balloon has shrunk to a minimal size, it is allowed to warm to room temperature. For college audiences, ask why the volume decreases to close to zero rather than about 1/4 of the volume as predicted approximately by Charles’ Law.
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 near the bottom of the bottle. A fountain will result and if sufficient nitrogen is used, it is possible to almost disappear in the descending fog. The rubber stopper should be held carefully as on rare occasions, liquid nitrogen runs down the glass tube and can freeze small portions of your fingers.
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.
Templates 2 and 3 for 8.5 inch x 11 inch
chromatography paper are on next pages.
1. Chen, P. S., Entertaining and Educational Chemical
Demonstrations, Chemical Elements Publishing
Co., 1974, 20.
2. American Flag Proportions, http://www.montney.com/flag/proportions.htm (accessed 03/05/09).
3. For example, see: The National Anthem: The Star-Spangled Banner,
http://www.usflag.org/thenationalanthem.html (accessed 03/06/09), The Star Spangled Banner
http://www.scoutsongs.com/lyrics/starspangledbanner.html (accessed 03/06/09), Star Spangled Banner.
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