I’m always looking for safer and cheaper options to perform chemical demonstrations, and I recently discovered a line of Elmer’s Glue products that support this pursuit. I shared three demonstrations using three Elmer glue products during the ChemEd X Demos Symposium at ChemEd 2023. These demos are explained here for those who couldn’t attend the conference.
Energy Transformation and Conservation
Energy is linked to several performance expectations in the NGSS Matter And Its Interactions standards (Figure 1). So, I like to use the following demonstration to review energy transformation near the beginning of the semester for students to draw on later. This demo is a modification of a classic demonstration, where Elmer’s Coloring Changing glue eliminates the need for some of the specialized equipment.
In the classic demonstration, a piece of paper is hit between two large steel ball bearings. The collision produces enough heat to burn a hole through the paper. In the classic demonstration, I ask a student volunteer to hold the paper and smell it immediately after the collision since a burning smell is noticeable. Although this classic demonstration version is fantastic, there are a couple of limitations. For one, only the student holding the paper can smell the burning paper, and the other students in the class may need convincing that the collision burned the hole and was not just torn. Additionally, 2-inch steel ball bearings can be expensive and require ordering from a specialized steel supply company.
In response to these limitations, I cover a piece of paper with an Elmer’s Color Changing glue product that changes from purple to pink when it gets warmer. After letting the glue dry, performing the same demonstration will form a bright pink circle at the site of the collision indicating the formation of heat (Image 1). The pink color slowly fades back to purple after a minute or two. Not only is the demonstration more visual with the Elmer’s glue product, steel ball bearings are no longer required, and the collision of any solid metal objects will produce enough heat to change the color of the glue. I like using 5-pound dumbbells, which make a larger pink circle visible even in a large room.
Image 1: Pink circles formed after collision of ball bearings.
Video 1: Upgrading a Classic Science Experiment - Burning Paper with Steel Ball Bearings, The Science Classroom YouTube Channel, February 2023.
Energy of Light
The energy of light and electrons are often studied together, and I like to start this topic with a demonstration to help students visualize the concept that different colors of light have different amounts of energy. Like the previous demonstration, I used an Elmer’s glue product to make the demonstration cheaper than the classic version. In the classic version of the demonstration, I ask the students to discuss who has the more powerful lightsaber: Darth Vader’s red lightsaber or Luke Skywalker’s blue lightsaber. After they make their predictions, I tell them I have a lightsaber energy detector that will glow more brightly when struck with a more powerful lightsaber. The detector is a phosphorescent vinyl sheet available from Educational Innovations and the lightsabers are made of a piece of white printer paper rolled around a red flashlight for Darth Vader and a UV flashlight for Luke Skywalker. To perform the test, turn off the lights in the classroom before removing the vinyl sheet from the protective cardboard sleeve (otherwise, it will already glow brightly from the overhead lights in the room). Once the lights are off, you can shine the red light over the vinyl sheet; nothing should happen. Then, shine the UV light, and the vinyl sheet will glow brightly.
Once again, this is an incredible demonstration on its own. Still, Elmer’s Color Changing glue with a pigment that changes color in the presence of sunlight (UV light) can make the demonstration less expensive and eliminate the need to turn out the lights. I cover a piece of foam board with the glue and let it dry. The glue-covered foam board produces a similar effect to the vinyl sheet by changing color when hit with UV light (Image 2).
Image 2: DIY lightsaber energy detector with Elmer's Color Changing glue.
Acid-Base Chemistry
In this last demonstration, Elmer’s Disappearing Purple glue stick is applied to a notecard revealing a secret message written in vinegar before the class period. The purple color in the glue stick comes from an acid-base indicator called o-Cresolphthalein which is purple at pH above 9.8 and colorless below. When the glue comes in contact with the dried vinegar, it rapidly changes colorless, surprising the students (Image 3). Since most students are familiar with the Disappearing Purple glue stick, this demonstration provides a short anchoring phenomenon to start an acid-base unit. After students are puzzled by the secret message during the demonstration, you can put them into small groups to see if they can replicate the phenomenon using various household acids and bases. Some products will intensify the purple color (base), and some remove the purple color (acid).
Image 3: Secret message is revealed with Elmer's Disappearing Purple glue
Video 2: How Does Elmer's Disappearing Purple Glue Work?, The Science Classroom YouTube Channel, August 2022.
NGSS
Students who demonstrate understanding can use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
*More information about all DCI for HS-PS1 can be found at https://www.nextgenscience.org/dci-arrangement/hs-ps1-matter-and-its-interactions and further resources at https://www.nextgenscience.org.
Students who demonstrate understanding can use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
Assessment is limited to main group elements. Assessment does not include quantitative understanding of ionization energy beyond relative trends.
Examples of properties that could be predicted from patterns could include reactivity of metals, types of bonds formed, numbers of bonds formed, and reactions with oxygen.
Students who demonstrate understanding can develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy.
*More information about all DCI for HS-PS1 can be found at https://www.nextgenscience.org/dci-arrangement/hs-ps1-matter-and-its-interactions and further resources at https://www.nextgenscience.org.
Students who demonstrate understanding can develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy.
Assessment does not include calculating the total bond energy changes during a chemical reaction from the bond energies of reactants and products.
Emphasis is on the idea that a chemical reaction is a system that affects the energy change. Examples of models could include molecular-level drawings and diagrams of reactions, graphs showing the relative energies of reactants and products, and representations showing energy is conserved.
Students that demonstrate understanding can develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.
*More information about all DCI for HS-PS1 can be found at https://www.nextgenscience.org/dci-arrangement/hs-ps1-matter-and-its-interactions and further resources at https://www.nextgenscience.org.
Students that demonstrate understanding can develop models to illustrate the changes in the composition of the nucleus of the atom and the energy released during the processes of fission, fusion, and radioactive decay.
Assessment does not include quantitative calculation of energy released. Assessment is limited to alpha, beta, and gamma radioactive decays.
Emphasis is on simple qualitative models, such as pictures or diagrams, and on the scale of energy released in nuclear processes relative to other kinds of transformations.