|MadSci Network: Chemistry|
OK. We want to prove that fire is energy, by proving it can do work. By work, for early-education purposes, we mean mechanical work, so if you can effectively demonstrate conversion of chemical energy to heat energy to mechanical energy, you will have demonstrated that fire is energy.
A good demonstration for this purpose would involve removing the engine from your car, and setting it up on a lab bench so that your students can examine-- just kidding.
But building a simple engine is quite easy, really. This site describes a fairly involved (~2-3 hours) project to build a simple engine that looks quite cute and has a neat ancient-greek-history angle as well, but just for illustrating the principle, you could do something extremely simple, like so:
I approve of your student's skepticism! :)
Hope this helps,
Dr. Edward J. Hyer
Naval Research Laboratory
Marine Meteorology Division
Monterey, California 93940
Try the links in the MadSci Library for more information on Chemistry.