Intermolecular Forces and FLIR Cameras

FLIR camera image using phone app

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Intermolecular forces is a topic that consumes a considerable amount of time in the chemistry curriculum. This one topic can carry over into bonding, nomenclature, modeling, labs and other areas. Intermolecular forces are often a challenge for students. Students struggle to make the connection between the particulate world of hydrogen bonding, London dispersion forces and the macroscale world of evaporation of compounds. There are many moving parts. These parts include the general relationship that shows more intermolecular forces the more energy required to boil and evaporate materials. Evaporation requires energy. The longer it a materials takes to evaporate, the less change in temperature is recorded. This relationship translates back to more intermolecular forces between molecules. Students really struggle with this idea. This multi level relationship involves many moving parts and the idea of energy which in itself is a big concept. FLIR cameras may help students with this complex concept.

FLIR cameras are an affordable method of recording temperature change and viewing the change in the infra red. There have been mentions of this method in this space before (check out Ben Meacham's blog, Seeing Chemistry in a Different Light—FLIR Thermal Cameras in the Classroom). A few years ago Travis Cole Green through Bowling Green State University also worked on the use of FLIR cameras in the high school classroom (check out this introductory video). I decided to use this idea in my classroom. I was able to get a small grant for some FLIR cameras from our local ACS educator's group and our school PTA. I received the cameras last spring as schools shut down and just now have been able to adapt and create a hybrid lab for students.

The goal of the lab was to examine the evaporation and intermolecular forces of four compounds. This lab was traditionally accomplished with temperature probes. Students wrap a piece of filter paper around the temperature probe and soak the paper in one of the liquids. The chemical with the weakest intermolecular forces evaporates faster. Faster evaporation produces a large drop in temperature. Slower evaporation  produces a small drop in termperature over a longer period of time. This is my attempt to recreate and adapt this lab with FLIR cameras.

I wanted to do this with six lab groups. I did not have enough petri dishes so I tested a quick adaptation. I cut up a bunch of filter paper into one by two inch rectangles. Each rectangle was labeled with a corresponding liquid. The paper was soaked in the liquid, placed on a lab bench and filmed with a FLIR camera. The results were fairly good and as predicted. Next, I had to convince six students to download an app on their phones.  Only a few students were willing to try the app and the camera. However, once they did and started "playing" with the camera, everyone wanted to try it. The engagement increased dramatically. We spent one class period learning how to use the cameras and talking about intermolecular forces. Each group labeled their four papers. The next day, students came in and I had their four papers soaking in respective liquids. They started recording with the infrared cameras as soon as the respective samples were placed on their lab benches. They recorded the video with their voices as a commentary. Students had the ability to go back and watch a relatively short recording to collect more data. Again, engagement was extremely high. One potential problem was that there was always one group that struggled with the technology. I had a pre recorded sampling that I did and I was able to send them the link. See video 1 below.

Video 1: FLIR and Evaporating Solvents, Chad Husting's You Tube Channel (accessed March 15, 2021)


Next came the post lab. Students were highly engaged on multiple levels. Some students had questions about the connections between the "coldness" of these solvents and what happens when they sweat or get out of a shower in the morning. Others noticed that the alcohol samples smelled like the "Doctor's Office". This lead to a discussion about the use of alcohol as a solvent to clean our skin before shots. They also noticed that it felt "cold" when that happened. There were also many unexpected connections. One parent wanted to know if his son could bring the camera home for the weekend so they could check their windows around their house to see if they were "leaking energy". Another unexpected connection was the clean up. All of the papers were easily disposed of accept the one soaked in oil. It left an oil slick on the lab tables. Never wanting to miss a teachable moment, we experimented with a couple of different soaps and found that shaving cream was the best method of cleaning up the oil of the tables. It is probably due to the long carbon chained stearic acid that has a little bit of polarity. Again, intermolecular forces in action.

The next day, students turned in the lab. The lab contained a question in which students had to predict what would happen if pentane had been used in the experiment. It provided a great opportunity to review intermolecular forces, evaporation, temperature and the relationships between all three. See video 2 for a recording for pentane.


Video 2: FLIR and Evaporation of Pentane, Chad Husting's You Tube Channel (accessed March 15, 2021)


Overall, I was satisfied with this first attempt of using FLIR cameras as an educational tool. There was high student engagement. It was easy to provide virtual components. This is a technology that can be widely adapted for a number of situations. I will continue to use these and hopefully have more to report in the future.


intermolecular forces, FLIR

Procedure time: 
30 minutes
Prep time: 
20 minutes
  • Four plastic petri dishes with lids (or equivalent shallow containers with lids)

  • Tap water

  • Canola oil (may be replaced with other oils)

  • Isopropanol (may be replaced with ethanol)
  • Methanol

  • Small squares of filter paper.

  • FLIR ONE Thermal Camera

  • *The free app is called FLIR ONE, available on Google Play Store or Apple App Store. You should use default mode settings*

  • If instructed, you may use another free app called Vernier Thermal Analysis for FLIR ONE. It is only available for iPhone and iPad.

  • *This product is available for both Apple and Android phones. The Android version connects to a mobile device using a standard micro-USB plug. Note that the Android device must support OTG (“On The Go”); check with your device specifications. The Apple connects using a Lightning plug (Apple devices built after September 30, 2012. i.e. iPhone/iPod Touch 5 and greater, iPads 4th generation and greater).*

  • Phone or tablet compatible with FLIR ONE Thermal Camera with app downloaded



Students will be working with four compounds to observe and compare their temperatures over time. The three compounds are: water, isopropanol (rubbing alcohol), methanol, and canola oil. Water and isopropanol are small molecules with defined structures. Canola oil is made up of triglycerides like that shown in Figure 1d.


table showing 4 liquids to be tested, water, isopropanol, methanol, canola oil

Four solutions to be used for activity.

Students will research and draw the structures of A, B and C. Triglycerides comprise a tri-ester of glycerol (the 3-carbon backbone at left) and three fatty acid chains that may differ between oils in terms of the number of carbons and the location of double bonds. The triglyceride that is shown (d) comprises two oleic acid (top, middle) and one linoleic acid (lower) chains attached to the glycerol backbone.

Before beginning the lab activity, students are asked to make a prediction about what they think will happen and provide an explanation justifying their prediction.

  1. Read the whole procedure for Activity 1 once to know what you‘re doing. Then begin to follow the steps.

    You will be provided with 4 filter papers. Label these with a pencil. Each should be labeled with Water, 2-Propanol, Methanol and oil.

  2. Connect your FLIR ONE Thermal Camera to your tablet/device and ​turn the camera on​. Open the FLIR ONE app and configure the following settings:

    1. Click on the Settings icon and make sure Celsius is selected for displaying temperature readings.

    2. Enable the crosshairs used by the FLIR ONE app to measure temperature by tapping the crosshair symbol located near the top of the app.

    3. Ensure the temperature scale is locked which can be accessed through the settings and clicking on “lock span”. Make sure that when you lock the scale that the field of view only includes the petri dishes and surrounding room temperature lab bench. The scale will be thrown off if any much warmer or colder objects are in view. Refer to the FAQ for additional help.

    4. Select the “Iron” color scheme for false-coloration of the app viewing screen.

  3. M​ake sure that both of you take turns to operate the FLIR One camera​ to record the experiment. Try to keep all papers in your field of view during the experiment. You should also maintain a consistent angle and distance for monitoring the petri dishes, and make sure that no warm object reflects stray IR light off the lab bench into the FLIR ONE camera during the procedure.

  4. There is a selection at the bottom of the FLIR ONE app to allow you to capture video when you are ready to begin. Once ready to begin, you will begin recording a 7-minute video of the papers.

  5. When you are ready to begin recording the video,put the papers down at once. Immediately start recording the video. Pan across the four compounds to record an initial temperature. Make sure you keep all dishes in the field of view during this process.

  6. During the recording, you should pan the view across the four papers so that the crosshairs displays the temperature of each compound everyone 1-2 minutes. You can stop recording video after 7 minutes.

  7. You don’t need to record temperature initially, just focus on observing changes any changes that you see. You will later go back and re-watch your video to record the data.

Students are instructed to transcribe data from their video into a graph and answer questions on the Student Document that can be found in the Supporting Information below.



See the Student Document in the Supporting Information below.


Set up stations with the FLIR camera, labeled containers holding the four solutions and filter paper strips.


Adapted from work by Travis C Green through Bowling Green State University.


General Safety

For Laboratory Work: Please refer to the ACS Guidelines for Chemical Laboratory Safety in Secondary Schools (2016).  

For Demonstrations: Please refer to the ACS Division of Chemical Education Safety Guidelines for Chemical Demonstrations.

Other Safety resources

RAMP: Recognize hazards; Assess the risks of hazards; Minimize the risks of hazards; Prepare for emergencies



Students who demonstrate understanding can Evaluate the validity and reliability of claims in published materials of the effects that different frequencies of electromagnetic radiation have when absorbed by matter.*

*More information about all DCI for HS-PS4 can be found at


Students who demonstrate understanding can Evaluate the validity and reliability of claims in published materials of the effects that different frequencies of electromagnetic radiation have when absorbed by matter. 

Assessment Boundary:

Assessment is limited to qualitative descriptions.


Emphasis is on the idea that photons associated with different frequencies of light have different energies, and the damage to living tissue from electromagnetic radiation depends on the energy of the radiation. Examples of published materials could include trade books, magazines, web resources, videos, and other passages that may reflect bias.

Students who demonstrate understanding can communicate technical information about how some technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture information and energy.*

*More information about all DCI for HS-PS4 can be found at


Students who demonstrate understanding can communicate technical information about how some technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture information and energy.

Assessment Boundary:

Assessments are limited to qualitative information. Assessments do not include band theory.


Examples could include solar cells capturing light and converting it to electricity; medical imaging; and communications technology.