Seeing Chemistry in a Different Light—FLIR Thermal Cameras in the Classroom

One of the inherent challenges of teaching chemistry is to make the invisible, visible. Often, we try to overcome this barrier by getting creative with a variety of models, animations, and simulations to help students think about chemistry in a way that is easier to conceptualize. The creative endeavor to make an abstract idea more concrete is a challenge that I’ve always loved pursuing. So, when I was presented with the opportunity to use some of our science budget to purchase a couple FLIR ONE thermal cameras, I was immediately curious about its potential for supplementing my instruction (see figure 1). To my surprise, having access to this piece of equipment has created several opportunities to experience the richness of chemistry in ways I had never been able to offer my students—or myself. While I know its potential applications in the classroom go well beyond my own, I wanted to share some of the ways I have found it to be helpful.

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Figure 1: FLIR ONE thermal camera

Before trying to use a piece of equipment, it’s worthwhile to have a basic understanding of how it works. To put it simply, FLIR cameras primarily deal with the infrared (IR) part of the EMR spectrum. The camera detects infrared energy (heat) and converts it into an electrical signal, which is then processed to produce a thermal image on a video monitor. Since all objects emit infrared energy to some extent, a thermal camera can easily detect differences in heat between objects in addition to quantifying that heat as a temperature reading.

Though the initial target audience for this technology may have been the military, it was only a matter of time before advancements in technology would allow for its use to cross over into a variety of avenues. The FLIR One camera is a wonderful example of this.

Depending on your need, FLIR offers three different types of connectors (USB-C, micro USB, and Lightning), which means it can connect directly to nearly any phone or tablet. If you are at a school with 1-to-1 iPads, this means any student would have the ability to use the camera on their own device. Using the FLIR ONE camera requires the free FLIR ONE app to work. The app is fairly easy to use, and it allows you to capture not only pictures, but videos as well. Additionally, you can record multiple temperature readings by touching any area on the thermal image. Once installed, it’s simply a matter of turning the camera on, opening the app, and start looking at the world.

Okay, enough background—how can this thing actually help teachers in the classroom?

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Figure 2: Dissolution of NaOH (left) and NH4Cl (right) as seen with FLIR One camera

Visualizing the heat of solution (endo/exothermic)

This was the first application that came to my mind. When I would demonstrate endothermic vs. exothermic processes in the past, I would simply dissolve two solutes, display the temperatures on the board up front, and students would see how temperature changed. It’s not like there is anything wrong with this; it gets the point across. However, this year I filmed the process with my FLIR camera and projected my phone screen to the board. Not only were students able to see the visual difference in thermal energy, they could still see the different temperatures as well. Combining these two pieces of evidence provided a much more fruitful conversation than in the past. In figure 2, you can see the infrared image we recorded while observing the dissolution of NaOH (left) and NH₄Cl (right).

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Figure 3: Crystallization of sodium acetate (right) compared to beaker of water (left)

Crystal Formation (Supersaturated Solution)

This was just awesome (see figure 3). The idea to film the crystallization of a supersaturated solution of sodium acetate was the product of one of those “I wonder if…” ideas (see video 1). Near the end of the video, I decided to lift the beaker up since I thought some of the energy released from the crystallization would have dissipated into the lab table. This moment was a perfect example of the potential for this tool to enable curiosity and make connections with different concepts.

Video 1: Supersaturated sodium acetate with FLIR camera (Ben's YouTube Channel - Published Nov. 8, 2019. Accessed 1/14/20)

Comparing Heat Absorption

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Figure 4: Thermal image of burning hot dog coated with fire gel

This was inspired by Tom Kuntzleman, co-author of the JChemEd article Creating and Experimenting with Fire Gel.¹ During our end-of-year research project, a group of students wanted to investigate the insulating ability of the superabsorbent polymer, sodium polyacrylate. The group combined this polymer with water to make a gel-like substance (fire gel) and coated a hot dog with it. The idea was to light two hot dogs on fire (one with and one without the fire gel coating). By doing this, the group was able to confirm Tom’s data and actually supplement the evidence with a visual of thermal energy. It was cool to actually see the insulating effects from this point-of-view.

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Figure 5: Comparison of hot dogs after burning with gel (left) and without gel (right)

Strength of Intermolecular Forces (Evaporative Cooling)

I haven’t done this with the FLIR camera yet, but I definitely plan to once we get to the appropriate unit. Usually, I’ve seen this demo done on a lab table and students are able to see the alcohol disappear before the water. Alternatively, some teachers have students place temperature probes in different solutions and then record differences in temperature while evaporating. Both approaches serve a useful purpose and allow for important inferences to be made. Supplementing this demo with a thermal camera brings in a new perspective, which was otherwise invisible. Evaporation of Water and Ethanol (with Thermal Imaging Camera) is an example of how a simple experiment on this topic could be performed.²

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Figure 6: Comparing the effectiveness of IR absorption by different greenhouse gases 

Comparing the Effectiveness of Different Greenhouse Gases

This idea was inspired by an activity from Pivot Interactives, and I absolutely love it. A group of students wanted the focus of their investigation to surround greenhouse gases. So, with a bit of guidance, I introduced them to the idea that they could trap various greenhouse gases in a bag and see how effective each gas is at absorbing infrared energy (figure 6). To do this, they simply placed the bag of gas in front of their face and captured a thermal image. If the gas does not absorb infrared energy all that well, that means more of it will pass through the bag and into the camera, resulting in their face to be visible. Conversely, if the gas absorbs infrared energy effectively, their face will appear nearly opaque since most of the energy was absorbed and not allowed to pass through the bag. I believe the gases that they tested were air, carbon dioxide, methane, and tetrafluoroethane. This was a really fun application and I enjoyed watching the group of students do this throughout their investigation.

I haven’t even had this FLIR camera for a whole year yet and I’ve already been convinced that it can supplement my instruction in ways that are directly beneficial to student learning and curiosity. Because it is easy to use, it lowers the threshold for experimental skills that may have been needed to conduct an authentic science investigation. I have no doubt there are hundreds of other ways to utilize this technology. So, if you have some ideas, please share!

CITATIONS

1. Kuntzleman, T.S., Mork, D.J., Norris, L.D., Maniére-Spencer, C.D., Creating and Experimenting with Fire Gel, an Inexpensive and Readily Prepared Insulating Material, J. Chem. Educ., 2013, 90, 7, 947-949. (accessed 1/14/20)

2. Evaporation of Water and Ethanol (with Thermal Imaging Camera), Collection of Physics Experiments, Department of Physics Education, Faculty of Mathematics and Physics, Charles University in Prague.