In my high school Chemistry class, the Ideal Gas Law was taught by showing students the equation, explaining the difference between ideal and real gases, and assigning several problems in which the ideal gas law is used.
This lecture-based approach encouraged surface learning, as students only had to memorize the behavior of gases rather than actually understand the reason for that behavior.
At the time, of course, I did not see a problem with this method of teaching and thought that I had a strong grasp on the topic. Not until I was a graduate student and teaching assistant (TA) in General Chemistry did I realize that I could benefit from further strengthening my understanding of such a fundamental concept.
Why Do Gases Behave the Way They Do?
As a lab TA, I often get asked “why.” Why does this happen? Why does this work the way it does? Why is this step necessary? I usually like questions that ask why because they demonstrate critical thinking skills and foster a deeper understanding. In one particular instance, however, I was asked to explain why gases behave the way they do, and – though I welcomed the curiosity – I felt embarrassed because I did not have a comprehensive answer. So I told my students I would do some more research on the topic and have a better answer for them during our next class.
Experimenting with Pressure, Volume, and Temperature
Later that day, I asked one of my colleagues the same gas law behavior question that my students had asked me. In response, she led me through an exercise that she had completed in her own undergraduate chemistry course. In the exercise, I chose a variable to isolate (e.g. the relationship between temperature and pressure) and made a hypothesis. We then designed and performed a simple experiment to test that hypothesis. Based on the data, I was able to deduce two other relative equations – Boyle’s and Charles’ Laws -and combine them to derive the Ideal Gas Law! After seeing exactly where the ideal gas law equation comes from, my perception and appreciation for the law expanded instantly. I reported this back to my students and showed them the connection using the same hands-on activity. It seemed to broaden their understanding as well, and even allowed them to answer their own question about why gases behave the way they do.
As a whole, this experience helped me realize that memorizing the Ideal Gas Law equation and the definitions of key terms is not a true science education;
A true science education is based on pattern recognition, problem solving, and scientific thinking.
My time spent exploring the basis of the Ideal Gas Law also made me wonder what challenges scientists and engineers were facing during the time of its discovery that led them to investigate the behavior of gases. I hope to learn more about the motivation behind this scientific breakthrough, as I believe it will provide solid contextual knowledge and add to my growing understanding of the ideal gas law.