A Demo A Day III: Demonstrations and Props Used in My General Chemistry II Classes

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 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.^1,2 This can difficult to achieve for every day of a course, but most meetings this past spring for my General Chemistry II classes had at least one of these physical examples. A comment about the way second-semester General Chemistry II has been run at Bradley University: Up through 2019, General Chemistry II was run as a four-credit course that met four times a week. Then, starting in the Spring of 2020 (yes, THAT spring), a quarter of the course was broken out into its own one-credit course called Chemistry of the Elements. That one-credit course meets once a week, covers chemistry of the metals, nonmetals, and a little bit of organic and polymer chemistry, and is now only required of our chemistry majors. General Chemistry II is now a three-credit course that meets three times a week. For the sake of simplicity, chemical examples from both courses are described in the listing below.

The demonstrations and props used in the Spring of 2023, and some previous years, are provided below. My motivation for using each example is also described. The demonstrations and props are categorized by their best fit to chapters in the course textbook (Tro, N. J. Chemistry: A Molecular Approach, 2020).³ This seemed to be a good starting point for categorizing the examples, recognizing that many of them fit into multiple categories. The descriptions are rather terse, but some of them have been described in more depth in other blog posts. Videos describing many of these examples are posted on the Chem Demos YouTube channel. These videos have been organized into categories, along with some discussion-promoting questions, on a Bradley University Chemistry Club Demo Crew website:⁴ 

Ch14 Solutions

Sodium acetate hand warmers ^1,5 – Showed a hand warmer containing supersaturated sodium acetate solution. When the metal disk inside was flexed, it became a nucleation site for the exothermic formation of crystals of solid sodium acetate. This was done to show crystals and their nucleation, supersaturation, and an exothermic process.

Two-phase bottle ^1,2,6 – 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. Also showed a plastic bottle containing a layer of yellow corn oil over a layer of water with blue food coloring, all with a little bit of dish soap added. When the bottle was shaken, the phases mixed. When the bottle became still, the phases eventually separated again, but much more slowly than when soap was not added. This was done to show polarity, solubility, the idea of “like dissolves like”, and the amphiphilic nature of soap.

Heat of solution for calcium chloride – Added calcium chloride containing ice-melting salt to water and monitored the temperature rise in the resulting mixture. This was done to show a salt with an exothermic heat of solution.

Baby carrots in regular vs salt water ¹ – Showed a carrot that had been soaked in tap water as being crisp and a carrot soaked in salt water as being soggy. This was done to show the impact of osmotic pressure on cells.

Orbees beads swelling in water – Showed sodium polyacrylate beads that had absorbed water, which made the polymer beads swell. This was done to show ion-dipole attractions that occur when an ionic compounds and water interact. The beads swell more in pure water than they do in salt water.

Dry erase marker person floating on water – Used a dry erase marker to draw a stick figure of person on a smooth plastic surface. Placed the plastic in water to lift the figure off the plastic and floating on the surface of the water. This was done to show that the nonpolar figure did not dissolve in the polar water.

Rusty BBs into soda and Lake Nyos ^1,3 – Showed a closed, sealed soda bottle and noted soda had no bubbles but there was a headspace with elevated carbon dioxide pressure. Opened the bottle and bubbles formed when the headspace pressure dropped and the carbon dioxide solubility of the soda decreased. Addition of rusty BBs to the soda nucleated the formation of more bubbles which caused foam to come out of the soda. Described the Lake Nyos carbon dioxide eruption tragedy as somewhat resembling the outgassing of soda. This was done to show Henry’s Law, where gas solubility decreased as the gas pressure decreased.

 

Ch15 Chemical Kinetics

Crystal Violet fade with varying concentrations of base ⁷ – Higher concentrations of base added to Crystal Violet solution cause the solution to fade more quickly. This was done to illustrate how higher concentrations of reactants can make chemical reactions proceed more quickly. 

Glowsticks in ice and warm water – Glowsticks placed in warm water glow brighter and fade away more quickly than glowsticks placed in cold water. This was done to show that chemical reactions move more quickly at higher temperatures.

Lycopodium powder in flame ^1,8 – Added lycopodium powder to a flame to produce a small fireball. This was done to show that higher surface area can produce faster reactions and to show an exothermic reaction.

Isotope shaker and catalyst rattle ^2,9 – Showed how lowering the barrier wall in a shaken, two-chambered container with a single type of beads will make it easier for those beads to get over the barrier.  This was done to illustrate how catalysts accelerate the rate of a chemical reaction by effectively lowering the activation barrier for a chemical reaction.

 

Ch21 Radioactivity and Nuclear Chemistry

Glow screen, laser colors, and radium samples ^1,2,10 – 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 different colors of light have different energies and that radium has similar chemistry to calcium (both are in Group 2 of the Periodic Table). See Online Activity: Chemical Kinetics and the “Radium Girls”.

Radioactive samples and Geiger counter ² – 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. 

Gamma irradiated glass marble and table salt – Used a Geiger counter to show that no significant radioactivity was produced by various irradiated samples such as a gamma-irradiated glass marble and table salt. This was done to illustrate various properties of radioactivity.

 

Ch16 Chemical Equilibrium

p-Dichlorobenzene in sealed bottle ^1,2 – Showed crystals of paradichlorobenzene that had sublimed from the bottom of sealed bottle and then deposited on the bottle walls, Figure 1. This was done to show an example of an organic compound with weak intermolecular forces that had likely reached its saturation vapor pressure in the closed bottle.

Figure 1. Crystals of p-dichlorobenzene in a sealed amber bottle  

 

Blue bottle reaction ^1,11 – Added potassium hydroxide to blue Gatorade to initiate oxidation of sugar by oxygen in the air. Color of Erioglaucine dye changed from blue to colorless as it was reduced by sugar and then back to blue as it was reoxidized by oxygen. This was done to show a system not at equilibrium with sufficiently slow reaction rates to enable better observations of the reactions.

Standing and balancing – Described the act of standing as an equilibrium. As a thought experiment, I noted that if someone were to come up and try to push me over (I stressed to the classes that this was a thought experiment only), then whether they succeeded or not, my body would probably try to resist the change to my equilibrium. This was shown as an analogy for LeChatelier’s Principle, where chemical systems at equilibrium tend to resist changes to that equilibrium.

NO₂ and N₂O₄ equilibrium tubes ² – 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 illustrate LeChatelier’s Principle.

Hand boiler ¹ – Showed liquid in two sealed glass bulbs at low pressure connected by a tube. When the heat of a hand was applied to one bulb, the vapor pressure in that bulb increased and pushed the liquid through the tube to the other bulb, where it fountained up and looked like it was boiling. This was done to illustrate LeChatelier’s Principle and to show the influence of heat on vapor pressure.

Bending and heating nitinol wire ¹² – Showed the superelastic and shape-memory behaviors of nitinol wire samples. This was done to show that the austenite/martensite phase changes associated with these properties of nitinol could be connected to LeChatelier’s Principle.

 

Ch17 Acids and Bases and Ch18 Aqueous Ionic Equilibrium

Turmeric and base – Powdered turmeric was added to water to make a yellowish mixture. Addition of base turns the curcumin in the turmeric to a reddish color. This was done to show acids and bases and indicators.

Secret message and hand turkey on special goldenrod paper and ammonia solution ^1,13 – Ammonia solution was sprayed onto special goldenrod indicator paper marked with some pattern drawn in colorless wax. Where the ammonia spray contacted the paper that was not covered by the wax, the paper changed from yellow to red. The waxed portions stayed yellow. Spraying the reddened paper with vinegar (acetic acid) turned it back from red to yellow. This was done to show acids and bases and indicators.

Anthocyanin-based indicators and acids and bases – Anthocyanin compounds were added to neutral water to produce a purple color.  Acids added to the mixture turned the anthocyanins to a reddish color, and bases added to the mixture turned the anthocyanins to a greenish and possibly even brownish color. There are many possible sources of anthocyanins including red cabbage, grapes, and many flowers, including lilac, phlox, butterfly pea, and chive. This was done to show acids and bases and indicators.

Slow antacid ¹ – Slowly added vinegar (acetic acid) to milk of magnesia (magnesium hydroxide suspension) and universal indicator in water. The purple or blue color of the indicator in the basic suspension changed through the colors of the rainbow to pink or red as the acidic vinegar was added. However, if only a small amount of vinegar was added at a time, excess solid magnesium hydroxide dissociated to make the solution basic again. If enough acid was added, either vinegar or some other acid, the magnesium hydroxide was completely consumed and the mixture stayed red. This was done to show acid and base and indicator color-changing reactions. Video 1 shows a variant of this demonstration using anthocyanins from phlox flowers.

Video 1. Slow antacid demonstration using anthocyanins from phlox flowers. ChemDemos YouTube Channel (accessed 5/17/2023)

 

Picture of local chemical plant that releases amine smell – Shown to connect the concepts of amines as bases to local experiences.

Hand turkey made from 2-propanol on thermal paper ^1,2,14 - A gloved hand was covered with 2-propanol or ethanol and placed on thermal paper, causing the dye inside the paper to react with acid in the paper and darken into a handprint image. This was done to show an example of acids, bases and indicators. See Thermal Paper as a Polarity and Acidity Detector.

Blow bubbles in indicator in water ² – Human breath was bubbled into water containing universal indicator. The carbon dioxide gas reacted with the water to produce carbonic acid which changed the color of the indicator. This was done to show that carbon dioxide can behave as an acid when mixed with water. Also, there is a connection to increasing carbon dioxide in atmosphere dissolving into oceans and making it more difficult for sea life containing calcium carbonate shells to survive. This demonstration in this course was also part of Bradley University’s participation in Bard College’s Worldwide Teach-in on Climate and Justice.¹⁵

Hydrochloric acid reacts with calcium carbonate but not granite ¹ – Placed calcium carbonate chalk into hydrochloric acid to produce carbon dioxide, water, and calcium chloride solution. Granite did not easily react with hydrochloric acid. This was done to show an acid and base and gas-producing reaction. Also, there is a connection to increasing carbon dioxide in atmosphere dissolving into oceans and making it more difficult for sea life containing calcium carbonate shells to survive. Figure 2 shows a traffic cone volcano variant of the demonstration.

Figure 2. Traffic cone “volcano” with hydrochloric acid and chalk pieces in the test tube

 

Sulfur-laden coal samples: FeSO₄ from FeS₂ ^1,2 - 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 to produce acidic nonmetal oxides.

Alka-Seltzer in film canister poppers ¹ – Placed a half-tablet of Alka-Seltzer (containing citric acid and sodium hydrogen carbonate) into a Fuji-style film canister filled halfway with water and closed the canister. The water dissolved the tablet and allowed the components to react to form carbon dioxide gas, water, and sodium citrate solution. After 10-30 seconds the carbon dioxide pressure built up and popped the canister apart. This was done to show an acid and base and gas-producing reaction.

Whack-a-Pack balloon ^1,16 – Struck a self-inflating balloon containing water, citric acid, and sodium hydrogen carbonate.  The components reacted to form carbon dioxide gas, water, and sodium citrate solution. The carbon dioxide inflated the balloon. The temperature of the liquid in the balloon dropped, due to the endothermic heat of solution of sodium hydrogen carbonate. This was done to show an acid and base and gas-producing reaction. See Expanding on Self-Inflating Balloons: Activities Involving Moles, Gas Laws, and Thermochemistry.

Powdered limestone for fields – Used to neutralize excess acidity in soil, this was shown as a reaction between carbonates and acids that some students might notice in rural fields.  

Sulfuric acid on nylon ^2,17 – 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.

Sodium nitrite in water and indicator – Shown as an example of a salt that is a combination of neutral cations and basic anions, which produce basic solutions when dissolved.

Borax snowflakes – The borax snowflakes were produced by dissolving the borax in hot water, and then letting the solution cool so that solid borax precipitates on chenille stems. The borax is also a salt that is a combination of neutral cations and basic anions, which produce basic solutions when dissolved. This was done to show salts that are not neutral and to show how temperature can impact solid solubility.

NaClO pen on goldenrod paper ¹³ – Wrote on special goldenrod paper with bleach pen. The paper turned red at first in contact with the basic bleach solution and then white as the dye is oxidized by the bleach. Shown as an example of a salt that is a combination of neutral cations and basic anions, which produce basic solution when dissolved.

Calcium sulfate crystal samples – Shown as an example of an ionic compound with low solubility.

Calcium fluoride samples – Shown as an example of an ionic compound with low solubility. Calcium fluoride, known as fluorite, is also the state mineral of Illinois.

 

Ch19 Free Energy and Thermodynamics

Light a flame ¹ – Lit a butane lighter. This was done to show the spontaneous exothermic reaction of the flame as a chemical system with everything else as surroundings.

Spontaneous assembly of spheres ¹⁸ – Spherical Air-Soft pellets were placed on the surface of salt water, where they assembled into a two-dimensional hexagonal array. This was used as a macroscale analogy for the formation of ordered solid from disordered liquid or solution, and to illustrate the relationships between changes in enthalpy, entropy, and Gibbs free energy.

Tulip in liquid nitrogen – Dipped a fresh tulip dipped into liquid nitrogen to freeze its water, enabling it to be spectacularly smashed. This was done to illustrate thermodynamic properties associated with the freezing of water.

International food energy ¹ – Showed wrappers showing energy values of food from other countries. This was done to show various energy units for food.

Magnet balls ¹ – Showed that bringing together attracting magnets releases energy, but pulling apart attracting magnets needs energy input. This was done to illustrate bond enthalpy.  Video 2 shows this demonstration.

Video 2. Demonstrating bond energy with magnets. ChemDemos YouTube Channel (accessed 5/17/2023)

 

Rubber band thermodynamics – Rubber band was stretched to warm it and allowed to relax to cool it and its temperature changes were felt by the upper lip. This was done to illustrate the relationships between changes in enthalpy, entropy, and Gibbs free energy.

UV beads ^1,2 – Showed photochromic beads that changed color when they absorbed UV light. This was done to show molecules absorbing UV light and that energy is absorbed when a bond is broken.

Iron based heat pack ^1,2 – 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 an example of an exothermic process. 

 

Ch20 Electrochemistry

Cleaning agent analogy to oxidizing and reducing agents – Used a white paper towel to clean off a dirty marker board, showing that the cleaning agent gets dirtier, not cleaner. This was shown as an analogy for the fact that oxidizing agents oxidize other species and are not themselves oxidized and fact that reducing agents reduce other species and are not themselves reduced. Video 3 shows this demonstration.

Video 3. Cleaning agent analogy to reducing and oxidizing agents. ChemDemos YouTube Channel (accessed 5/17/2023)

 

Chromium(VI) ethanol sensor – This alcohol in human breath sensor worked by ethanol reducing yellow chromium(VI) species to green chromium(III) species. This was shown to supplement a redox reaction balancing exercise.

Silver nitrate oxidizes copper metal ¹ – Placed a copper penny or strip of copper metal into a solution of silver(I) nitrate to illustrate a redox reaction. The silver(I) ions were reduced to form fuzzy silver metal crystals and the copper metal was oxidized to produce blue copper(II) ions. This was done to show a redox reaction.

Human salt bridge – Connected a copper strip and a zinc strip to a voltmeter, but no voltage was produced until both strips are touched by a hand. This was done to show the importance of a salt bridge in electrochemical cells. 

Vitamin C reduces iodine in starch complex ¹ – Starch was added to brown iodine solution to produce a dark purple-black starch-iodine complex. Then, Vitamin C (ascorbic acid) was added to reduce the iodine complex to colorless iodide ions. This has been done in the palm of a hand, but can also be done in glassware. This was done to show a redox reaction.

Open lead acid car battery ³ – Shown to illustrate the six chambers and lead electrodes in a typical car battery.

Alkaline battery ³ – Shown to illustrate the zinc can, graphite electrode, and manganese(IV) oxide paste in a typical alkaline battery.

Fuel cell car with hydrogen, oxygen, and water bond models ^1,19 – Showed a hydrogen-oxygen fuel cell providing electricity to move a motor and wheels. The hydrogen and oxygen gases had been produced by using external batteries and the same assembly to electrolyze water. Used drawings to show bonds breaking and forming in the reversible reaction of water to form hydrogen and oxygen. This was done to illustrate bond enthalpy and reaction spontaneity in electrochemical processes.

MudWatt battery ¹ – Purchased as a kit, bacteria in mud catalyzed the redox reaction between oxygen in the air and organic matter in mud. Electrons from this reaction were used to make an LED blink. This was done to show a redox reaction.

Iron vs aluminum beverage cans – This was done to show how iron corrodes differently (with orange portions that flake off) differently than aluminum corrodes (with a thin invisible oxide that adheres to the aluminum).

 

Ch22 Organic Chemistry

Dry ice in indicator solution ¹ – Dry ice was added to water containing universal indicator. The carbon dioxide gas reacted with the water to produce carbonic acid which changed the color of the indicator. This was done to show the weakness of London forces between molecules in solid carbon dioxide as it sublimes to the gas state, and also that carbon dioxide can behave as an acid when mixed with water.

Alkane samples – Showed a variety of alkanes. Those with the least number of carbons per molecule were gases at room temperature, those with the most number of carbons per molecule were solids at room temperature, and those with intermediate numbers of carbons were liquids at room temperature. This was done to show the effects of molecular size on intermolecular forces. 

p-Dichlorobenzene in sealed bottle – See previous description. This was shown as example of a compound that contains carbon-halogen bonds, and to show an example of an organic compound with weak intermolecular forces that had likely reached its saturation vapor pressure in the closed bottle.

Empty can of R-134a air conditioner refrigerant ² – Showed an empty bottle that once held R-134a air conditioner refrigerant. This was shown as example of a compound that contains carbon-halogen bonds, and was shown as part of a comparison of the global warming potential between R-134a and carbon dioxide. This demonstration in this course was also part of Bradley University’s participation in Bard College’s Worldwide Teach-in on Climate and Justice.¹⁵

Plastics with resin codes 1 through 7 ² - 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.

 

Ch24 Chemistry of the Nonmetals

NO₂ and N₂O₄ equilibrium tubes – See previous description. This was done to show an example of a nitrogen oxide, and dinitrogen tetraoxide has been used with hydrazine compounds as rocket propellant.

Hydrazine compound – This was done to show an example of a nitrogen compound, and hydrazine compounds have been used with dinitrogen tetraoxide as rocket propellant.

Carbon allotropes and models – This was done to show the variety of carbon allotropes, including graphite, diamond, fullerenes, and carbon nanotubes.

Quartz crystal vs window glass ¹ – This was done to compare these silicon oxide based network covalent compounds. The quartz is crystalline and the glass is amorphous.

Light-emitting diode in liquid nitrogen ¹² – Placed the “flame” of a yellow-glowing LED tea light into liquid nitrogen, turning its glow more greenish in color. This was done to show that the low temperature decreases the distance between the atoms and increases the bandgap of the LED semiconductor, and to show that semiconductor behavior (and LED color) can be impacted by the elements that it contains.

Calcium carbonate and hydrochloric acid – See previous description. This demonstration in this course was also part of Bradley University’s participation in Bard College’s Worldwide Teach-in on Climate and Justice.¹⁵

 

Ch24 Metals and Metallurgy

Metal vs. nonmetal part of desk ¹ – Had students place their hand on a metal part (e.g., a leg) of their desk and also on a nonmetal (e.g., wooden or plastic seat or writing surface) of their desk and asked the student to observe which parts felt colder than the others. The metal parts of the desk felt colder than the nonmetal parts because the metal parts conducted heat from their hands more quickly than the nonmetal parts. This was done to show the difference in thermal conductivity between metals and nonmetals.

Liquid metal bounce – Bounced metal spheres from a stainless steel surface and an amorphous alloy surface. The rebound of the metal sphere from the disordered amorphous alloy is much higher. This was done to illustrate alloys, their structures, and their properties.²⁰

Bauxite and aluminum metal ² – These were shown to help illustrate the process of aluminum production from bauxite. The reddish color of transition metal iron in the bauxite sample lent itself to the description of the red mud byproduct of bauxite purification.

Taconite balls ²¹ – These were shown as examples of how iron ore is transported for eventual reduction to produce steel.

Pineapple can with zinc interior – This was shown as an example of a zinc-coated surface.

Mr. Yuk stickers ²² – These were shown as an example of an older way to present chemical safety to the public, sometimes with rather creepy TV commercials.

Red Peeps ²³ – These were shown as an example of a food additive (Red #3) with a controversial safety record.

Inorganic complex isomer models – These models were shown to illustrate cis-trans, mer-fac, and optical isomerism.

Left-handed handshake – Offered to shake someone’s hand using a left hand, and they responded by offering their left hand. This was done to illustrate how molecules sometimes must have the correct chirality in order for them to interact.

Colorful transition metals vs colorless main group metals ¹ – Showed samples of compounds of transition and main group metals. This was done to illustrate that the electronic structure of metal ions influences their colors.

K₄[Fe(CN)₆)] solution and other transition metal complex samples – Showed samples of the complexes as part of a description of why they have their specific colors, and to make nomenclature a little more interesting.

Egg crate model of octahedral crystal field splitting diagram ²⁴ – Used a cut-up egg carton to represent d orbital energy levels and halves of plastic eggs to represent electrons. This was done to illustrate how electrons were distributed in d orbitals undergoing high field and low field splitting.

 

Other

Algae chlorophyll fluorescence ²⁵ – A 405 nm laser pointer was used to cause the chlorophyll in algae to fluoresce pink. This was done in preparation for Chemists Celebrate Earth Week. See Algae Connections to Chemistry Classrooms.

 

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 and the Illinois Space Grant Consortium. Special thanks to Audrey Stoewer for developing the video website.

References

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2. Campbell, D. J. “A Demo A Day II: Demonstrations and Props Used in My Environmental Chemistry Class.” ChemEd Xchange. December 3, 2022. https://www.chemedx.org/blog/demo-day-ii-demonstrations-and-props-used-m... (accessed May, 2023).
3. Tro, N. J. Chemistry: A Molecular Approach, 5th Edition; Pearson Education, Inc., 2020.
4. Bradley University Chemistry Club. Demo Videos. https://sites.google.com/mail.bradley.edu/bradleychemdemos/demo-videos (accessed May, 2023).
5. Campbell, D. J. Chem Demos You Tube channel. Reusable heat packs containing sodium acetate and water. https://youtu.be/BlmvWyGdDDQs (accessed May, 2023).
6. Campbell, D. J. Chem Demos You Tube channel. Two phase "wave" bottles demonstrate density, polarity, and soap. https://www.youtube.com/watch?v=jASD-xooP2E (accessed May, 2023).
7. Campbell, D. J. Chem Demos You Tube channel. Crystal violet fade. https://www.youtube.com/watch?v=DCUkKpKCaHc (accessed May, 2023).
8. Campbell, K.M.; Campbell, D. J. Chem Demos You Tube channel. Lycopodium Dragon Sneeze with a Face Maskhttps://www.youtube.com/watch?v=8fmVs4J3IuM (accessed May, 2023).
9. 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.
10. Campbell, D. J.; Lojpur, B. “Online Activity: Chemical Kinetics and the Radium Girls.” ChemEd Xchange. December 20, 2021. https://www.chemedx.org/blog/online-activity-chemical-kinetics-and-%E2%8... (accessed May, 2023).
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17. 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.
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19. Campbell, D. J. Chem Demos You Tube channel. Demonstrating bond energy, fuel cells, and hydrogen combustion. https://youtu.be/4q1_mdRNCTg (accessed May, 2023).
20. Campbell, D. J. Chem Demos You Tube channel. Substitutional, interstitial, and amorphous alloys. https://youtu.be/SHNTK373-MY (accessed May, 2023).
21. Minnesota Department of Natural Resources. Taconite. https://www.dnr.state.mn.us/education/geology/digging/taconite.html (accessed May, 2023).
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23. Nicioli, T. CNN.com. Popular Easter candy Peeps contains additive linked to cancer, Consumer Reports says. https://www.cnn.com/2023/04/07/health/red-dye-no-3-peeps-wellness/index.... (accessed May, 2023).
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