A Demo A Day II: Demonstrations and Props Used in My Environmental Chemistry Class

River in northern Wisconsin tinted brown with tannins

Dean J. Campbell*

*Bradley University, Peoria, Illinois

Classroom demonstrations have long been an approach used to convey information in chemistry courses. The intent is to help student learning by providing physical or video examples to illustrate concepts described in class. It has been my goal to show at least one of these examples per class meeting time in all of my courses. I have been mostly successful in recent semesters, since there are so many connections that can be made. It does help to write down what examples are used for each course and then refer to the list in subsequent offerings of the course. Examples used for Fall 2022 and Fall 2018 offerings of Environmental Chemistry are briefly described below. Many of these examples are also suitable for use in high school and collegiate General Chemistry courses. My motivation for using each example is included in the list. The examples are categorized by their fit to sections of the course that in part follow the sections in the course textbook (Baird, C.; Cann, M. Environmental Chemistry, 5th ed., 2012).1 This seemed to be a good starting point for categorizing the examples, recognizing that many of them fit into multiple categories.

For more demo ideas see Dean's previous post - 

The descriptions are rather terse, but some of them might become integrated into future blog posts. Videos describing many of these examples are posted on the YouTube channel Chem Demos. These videos have been organized into categories, along with some discussion-promoting questions, on a Bradley University :2 

 

Section 1 – Introduction to Environmental Chemistry and Green Chemistry

“Field trips” to the General Chemistry laboratory and to the chemical stockroom – This was done to illustrate that many of the physical features in the lab and stockroom were designed to minimize risk to the students and faculty by minimizing their exposure to chemicals. Lab features included fume hoods and safety goggles and stockroom features included ventilated cabinets, gloves, and spill cleanup equipment. These features were not as obviously focused on minimizing risk by minimizing the inherent hazards of the chemicals themselves, which is more of a Green Chemistry approach. Whether or not the students had previously taken General Chemistry lab courses at Bradley University or seen the stockroom, it was useful to show them the spaces through the lens of Environmental Chemistry.

12 Principles of Green Chemistry bookmarks to each student – Acquired at a conference, this was done to help the students to remember the 12 Principles of Green Chemistry.

Various environmental science books and handbooks such as the Merck Index – This was done to show the students additional examples of Environmental Chemistry resources. The Merck Index was shown as a place to find LD50 values and other toxicological information.

Fifty-year old chemistry set designed for at-home use – This was done to point out outdated views on safety and possibly outdated views as to who might be the anticipated users of such kits. An old bottle of ferrocyanide salt from the kit was shown as an example of a chemical sample that persisted beyond the useful lifetime of the kit, but did not seem to have a disposal plan associated with it.

“Field trip” to the Department of Chemistry and Biochemistry student resource center and its Chemical & Engineering News issues - This was done because not all of the students were familiar with the resource center and the C&EN issues housed there, and several times throughout the course, students were directed to environmentally-related articles in C&EN.

Samples of catalysts from my research lab – This was done to provide students with a connection to Catalysis (one of the 12 Principles of Green Chemistry) and a connection to a current research project.

Nitrous oxide (Whip-It) canister – Showed an empty canister found in a parking lot.

This was done to inform the class about the illegal practice of inhaling this gas and to illustrate the concept that chemical species can get into the bloodstream very quickly via the lungs.3

Chem Hat website – This was done to show students a free website () that could be used to look up hazard information for a variety of chemical compounds.4

 

Section 2 – Environmental Chemistry of the Air and Energy Production

LEGO brick atmosphere sticks – Showed stacks of LEGO bricks with color schemes representing the gases in the atmospheres of Venus, Earth, and Mars. This was done to illustrate discussions of mole percent and show differences between some planetary atmospheres.3

Oudin coil discharge changing wettability of surface of plastic dish – Placed the tip of an Oudin coil near a plastic Petri dish and used the high voltage discharge of the coil to oxidize the surface of the dish. Moved the coil tip from the dish surface and then sprayed the dish surface with a water mist. Where the water landed on the untreated plastic dish, it beaded up to form separate water drops on the hydrophobic surface. Where the water landed on the surface that had been treated by the coil discharge, it spread out on the hydrophilic surface and individual water drops were indistinguishable. This was done to illustrate how high voltages can produce oxidizing species in the air such as ozone.5  

Ozone hole video website – Showed the 6 and the movies of the maps of the southern hemisphere ozone hole. This was done to demonstrate the typical progression of the formation of the ozone hole in the southern hemisphere.

UV beads – Showed UV light absorbing, photochromic beads. This was done to show molecules absorbing UV light.3,7

NO2 to N2O4 equilibrium tubes – Showed closed glass tubes that contained orange mixtures of NO2 and N2O4 gases and showed that the tube color lightened when the temperature decreased (decreasing the concentration of the orange NO2 and increasing the concentration of the colorless N2O4). This was done to show students the orange-brown color of photochemical smog and one of many gas phase reactions.

FeSO4 from FeS2 - Showed a sample of marcasite (FeS2, similar to pyrite) that had been oxidized in air to melanterite (FeSO4). This was done to show some of the reactions that can happen in local coal formations and to show how easily sulfur compounds in fossil fuels can be oxidized.

Sulfuric acid on nylon – Showed that swatch of nylon fabric disintegrated in contact with 6 M sulfuric acid. This was done to illustrate the story of sulfuric acid forming on ash particles produced at a local coal-fired power plant years ago and landing on nylon stockings, causing them to fall apart.8 See Video 1.

 

Video 1. Remembering the day the nylons ran in Peoria. Chem Demos YouTube channel (accessed 11/27/2022).

 

Powdered limestone from farm field – This was done to show how some farmers use agricultural lime to decrease acidity in the soil in their fields.

Coal fly ash and Mt. St. Helens ash samples – This was done to show the similarities and differences in the combustion-produced fly ash and the volcanically-produced Mt. St. Helens ash, both examples of airborne particulate matter.9

Sample of banded iron formation – This was done to show the catastrophic changes in the Earth’s geochemistry resulting from the rise of oxygen in the atmosphere. See Video 2.

 

Video 2. A banded iron formation rock. Chem Demos YouTube channel (accessed 11/27/2022).

 

Asbestos sample – This was done to show the fibrous structure of asbestos, which can be a source of hazardous airborne particulate matter.

Catalytic combustion apparatus – Though the specific directions for the demonstration have been long lost, the apparatus was used to describe the general principles of catalytic combustion.

Plastic bottles filled at high-altitude – Showed plastic water bottles filled with air at the summit of Pike’s Peak and in the cabin of an airplane cruising at about ~35,000 feet, then sealed, and then brought back to the altitude of Peoria, IL.3 This was done to show how the volume of a sample of gas changes with different pressures at different altitudes. See Video 3.

 

Video 3. Pikes Peak bottle in vacuum. Chem Demos YouTube channel (accessed 11/27/2022).

 

Incandescent light on dimmer switch – Showed how the glow of an incandescent bulb changed as the applied voltage was varied. This was done to illustrate the general relationship between temperature of an object and its blackbody radiation, which is useful for understanding the greenhouse effect.

Isotope shakers – Showed the difference in the ability of lightweight beads and heavyweight beads to move over a barrier wall in a shaken, two-chambered container.L This was done to illustrate how isotope distributions can provide information about the temperature history of the Earth.10

Empty can of air conditioner refrigerant – Showed an empty bottle that once held R-134a air conditioner refrigerant. This was done as part of a comparison of the global warming potential between R-134a and carbon dioxide.

YouTube video of heat pack contents in bottle (could have done this as a live activity) - Poured the contents of an iron powder based heat pack into an empty plastic water bottle. As the iron powder removed the oxygen from the air in the bottle to form iron oxide in an exothermic reaction, the bottle collapsed. This was done to show there is some oxygen in the air and that as the moles of a gas decreases so does its volume (Avogadro’s Law). 3.11 See Video 4.

 

Video 4. Oxygen removal from bottle by heat pack iron (graduated cylinder and time lapse). Chem Demos YouTube channel (accessed 11/27/2022).

 

Animated Engines website – This 12 was used to show the similarities and differences between two-stroke, four-stroke, and Diesel engines.

Ethanol plant products – This was done to illustrate that the use of corn to produce ethanol also produces many other useful products.

LED tree that plugs into laptop – Showed a little decorative tree that plugs into my computer to light up in various colors due to its LEDs. This was shown as an example of Jevon’s paradox, where decreases in energy usage by devices (e.g. by switching to LEDs from other light sources) are at least partially offset by the increasing number of devices that use LED lighting.

Glow screen, lasers, and radium girl statue – Shined red, green, and violet lasers on glow in the dark screen (only violet makes the screen glow significantly). Told the story of the painters who died of radium contamination and showed a picture of the “radium girl” memorial in Ottawa, IL. This was done to show how radium has similar chemistry to calcium (both are in Group 2 of the Periodic Table).3,13

Radioactive samples and Geiger counter – Used a Geiger counter to measure the radioactivity produced by various radioactive samples such as trinitite and uranium-containing Fiestaware. This was done to illustrate various properties of radioactivity.

Section 3 – Environmental Chemistry of Water

Exhale bubbles into deionized vs. tap H2O with indicator – Universal indicator was added to samples of deionized water and tap water, and breath was bubbled into the water using a straw. The deionized water changed color to acidic pH much more easily than tap water. This was done to show how the carbonates in the tap water can, to some extent, neutralize acidity.

 

Figure 1. River in northern Wisconsin tinted brown with tannins 

 

Tannin-rich water from northern Wisconsin – This was done to show an example of natural surface water that rich in suspended organic matter. See Figure 1. Brown in color, yet mostly transparent, this is quite different than some of the cloudy, clay laden waters in Central Illinois.

Water softener resin and limestone samples – These were used to help illustrate discussions about water hardness and how water softeners work, with limestone as a source of calcium ions in water and the resin as a way to remove calcium ions from water.

Soft vs. hard water shaken with soap – Two bottles, one half-filled with deionized water and soap, and the other half-filled with water containing calcium ions and soap, were shaken. The bottle that did not contain the calcium ions produced much more foam. This was done to show how calcium ions can interfere with the effectiveness of soap.

Bleach and black fabric – A bit of sodium hypochlorite laundry bleach is added to black fabric to bleach it. This was done to show the oxidizing power of bleach and to help illustrate why it is used as a disinfectant.

Picture of grandfather with World War I attire – This was done because it was around Veterans Day, and there are many connections that can be made between the military and the environment, including the toxicity of chemical warfare agents and environmental contamination associated with military operations such as at Camp Lejeune, burn pits, Agent Orange, DDT,…the list goes on.

2-phase bottle - Showed a plastic bottle containing a layer of yellow corn oil over a layer of water with blue food coloring. When the bottle was shaken, the phases mixed. When the bottle became still, the phases separated again.3 This was done to show polarity, solubility, and the octanol-water partition coefficient (Kow). The yellow pigments of the corn oil would be expected to have a large Kow and the blue pigment would be expected to have a small Kow.

Raid insecticide – This was shown as an example of pyrethroid insecticide.

para-Dichlorobenzene and Sucralose sweetener samples – These were shown as examples of compounds with carbon-chlorine bonds.

Mixing chamber for making dental alloy – This was done to supplement discussions of mercury, and how it was used in alloys for fillings in teeth. There is also a Green Chemistry connection, in that mixing chambers have been explored for use in solvent-free mechanochemical processes.

Hand turkey made from 2-propanol on thermal paper - A gloved hand was covered with 2-propanol and placed on thermal paper, causing the dye inside the paper to darken into a handprint image. This was done as part of a description that many types of thermal paper contain bisphenol-A, used as an acid to darken the dye in the paper.14 See  and Video 5.

 

Video 5. Hand turkey from 2-propanol on thermal paper (time-lapse). Chem Demos YouTube channel (accessed 11/27/2022).

 

Section 4 – Environmental Chemistry of Land

Tiles from old science building – This was done to show an example of construction waste, with the twist of describing what the science building used to look like with all of those brown tiles on the interior walls.

Bauxite and aluminum metal – This was done to help illustrate the process of aluminum production from bauxite. The reddish color of the bauxite sample lent itself to the description of the red mud byproduct of bauxite purification.

Plastics with resin codes 1 through 7 - Polymer samples all attached to one board with labels of the resin code and polymer name, this was done to show examples of polymers for each of resin codes 1 through 7.

 

Safety 

I have worked to maximize safety, but each demonstration and prop comes with its own particular set of safety considerations. If physical classroom examples are to be done in-person, then instructors must identify and respond to potential hazards, personal protective equipment, and disposal issues associated with these examples.

 

Acknowledgements

This work was supported by Bradley University and the Mund-Lagowski Department of Chemistry and Biochemistry with additional support from the Illinois Heartland Section of the American Chemical Society. The material contained in this document is based upon work supported by a National Aeronautics and Space Administration (NASA) grant or cooperative agreement. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author and do not necessarily reflect the views of NASA. This work was supported through a NASA grant awarded to the Illinois/NASA Space Grant Consortium. Special thanks to Audrey Stoewer for developing the video website.

 

References

  1. Baird, C.; Cann, M. Environmental Chemistry, 5th Edition; W. H. Freeman and Company: New York, 2012.
  2. Bradley University Chemistry Club. Demo Videos. https://sites.google.com/mail.bradley.edu/bradleychemdemos/demo-videos (accessed November, 2022).
  3. Campbell, D. J. “A Demo A Day: Demonstrations and Props Used in My General Chemistry Class.” ChemEd Exchange. https://www.chemedx.org/blog/demo-day-demonstrations-and-props-used-my-g... (accessed November, 2022).
  4. BlueGreen Alliance. ChemHAT.org. Chemical Hazard and Alternatives Toolbox. https://chemhat.org (accessed November, 2022).
  5. Campbell, D. J.; Olson, J. A.; Calderon, C. E.; Doolan, P. W.; Mengelt, E. A.; Ellis, A. B.; Lisensky, G. C. "Chemistry with Refrigerator Magnets: From Modeling of Nanoscale Characterization to Composite Fabrication." J. Chem. Educ., 1999, 76, 1205-1211.
  6. Nash, E. R. NASA Goddard Space Flight Center. NASA Ozone Watch. https://ozonewatch.gsfc.nasa.gov/SH.html (accessed November, 2022).
  7. Campbell, D. J. “Photochromic glue and spring decorations.” ChemEd Exchange. https://www.chemedx.org/blog/photochromic-glue-and-spring-decorations (accessed November, 2022).
  8. Campbell, D. J.; Wright, E. A.; Dayisi, M. O.; Hoehn, M. R.; Kennedy, B. F.; Maxfield, B. M. “Classroom Illustrations of Acidic Air Pollution Using Nylon Fabric.” J. Chem. Educ., 2011, 88, 387-391.
  9. Campbell, D. J. “Mt. St. Helens 40 Years Later: Getting More from Soda Volcano Demonstrations.” ChemEd Exchange. https://www.chemedx.org/article/mt-st-helens-40-years-later-getting-more... (accessed November, 2022).
  10. Campbell, D. J.; Brewer, E. R.; Martinez, K. A.; Fitzjarrald, T. J. "Using Beads and Divided Containers to Study Kinetic and Equilibrium Isotope Effects in the Laboratory and in the Classroom." J. Chem. Educ., 2017, 94, 1118-1123.  
  11. Campbell, D. J.; Bannon, S. J.; Gunter, M. M. “Gas Property Demonstrations Using Plastic Water Bottles.” J. Chem. Educ., 2011, 88, 784-785.
  12. Keveney, M. Animated Engines. http://animatedengines.com/ (accessed November, 2022).
  13. Campbell, D. J.; Lojpur, B. “Online Activity: Chemical Kinetics and the Radium Girls.” ChemEd Exchange. https://www.chemedx.org/blog/online-activity-chemical-kinetics-and-%E2%8... (accessed November, 2022).
  14. Campbell, D. J.; Lojpur, B.; Liu, R. “Thermal Paper as a Polarity and Acidity Detector.” ChemEd Exchange. https://www.chemedx.org/blog/thermal-paper-polarity-and-acidity-detector (accessed November, 2022).