Tag Archives: dissolving

Infrared imaging for chemistry education

Infrared (IR) imaging is a technique for seeing heat based on detecting thermal radiation (mostly IR) an object emits. It used to be a very expensive tool only affordable to guys in military and secret services where money is not a problem.

You can now buy "lower"-grade IR cameras with $1,500-$2,500, which are pretty cool (thank you for lowering down the prices, Flir and Fluke!). There is a vast market for this technology. Engineers and technicians buy them primarily for checking heat flow in building, electrical systems, and mechanical systems. Companies also use them to do quality assurance and safety monitoring.

I have been digging the educational potential of IR imaging lately. I feel that the tool can be very useful in education. Compare it with a microscope. Both can be used to see something invisible. In the case of a microscope, it is things that are too small to be seen. In the case of an IR camera, it is things that our eyes cannot detect. It is obvious that students need a microscope to see small things. But perhaps we can also rationalize the need for an IR camera in the classroom? What are the most important things that IR imaging can teach?

Obviously there is heat transfer. I have recently written a paper about this. But I don't want to just do the evident ones. So I have been thinking about how to broaden its applications. A direction I am taking now is its applications in chemistry, where heat is a central concept. You probably still remember that your high school chemistry teacher always wanted you to remember how much heat is released or absorbed in a chemical reaction. If a reaction produces a dramatic effect, such as a bang or a flash or a flame, then you probably were impressed. What about those reactions that mostly go unnoticed unless some sensitive methods are used to show them? For instance, most biochemical processes are pretty "calm." How does one "see" or "hear" them?

I have done an experiment that uses an IR camera to show evaporation and condensation, as mentioned in the paper. The above IR thermogram shows what happened when a piece of paper was placed on top of a cup of water. The paper did not fully cover the cup. What we see from this IR image is a cooler area that shows the evaporation process of the water in the cup and a warmer area that shows the condensation process of the water on the other side of the paper.

Last week, I did another experiment to prove that it can also be used to visualize dissolving. This experiment is introduced in a short article. The image to the right shows the thermograms of three cups: pure water, table salt solution, and baking soda solution, shortly after table salt and baking soda were added to two of the cups originally filled with pure water.

I am hoping to devise more chemistry experiments to prove the versatility of this powerful tool in making mysterious things in chemistry visible. I intuitively feel that this tool, which is essentially a bundle of thousands of IR thermometers, may be able to release students from tedious lab procedures and make chemistry experiments easier to conduct and fun to look at.