The Octane Cannon Experiment Updated for Television The octane cannon experiment' is a well known general chemistry demonstratian. In this experiment a piece of glass tubing is fitted with 2 corks. The lower cork has 2 small nails through it. The upper cork is removed, the tube is flushed with oxygen, a few drops of liquid octane are added to the tube and the cork is replaced. When a Tesla eoil is placed near one of the small nails, the cannon explodes, and the corks fly across the room. We have updated this demonstration for use with a simple television system, consisting of a monitor, a camera, and a recorder. We have used SONY equipment, but any comparable apparatus is also suitable. The television camera shoots the experiment while it is being performed live for the students. The students can either look at the monitor(s) or the actual experiment, depending on student location, class size, ete. The experiment is then rerun with the television recorder. Just before the Tesla eoil ignites the cannon, the pause switch on the recorder is activated and the TV picture is frozen on the screen. By slowly turning the TV tape reels by hand individual frames can be put on the screen. By this technique, a "stop action" replay illustrating the major parts of the explosion can be shown to the students. The extent to which you can observe various stages of the explosion depends an the time constant of your frames. The one we have is about 0.033 sec.
Figure 1. Slde view photographs of indlvldual teiev8sion frames.
Figure 2. End view photographs of ndividuai television frames.
Figure 1 shows some photographs we have taken of individual frames from our TV screen during the "stop action" replay. The upper left photograph is the apparatus prior to explosion. The upper right shows the explosion just starting and the shock wave or light flash only extending a portion of the way up the tube. The lower cork is already gone, while the upper cork is still intact. The lower left is the very next frame (about 0.033 sec later) and the tube is already complitely aglow and both corks are gone. A shadow af the upper cork can still be seen. The lower right photograph was taken several frames later, and shows the explosion dyingdown. Figure 2 shows four comparable photographs taken from a different angle. In the upper left, the Tesla eoil tip can be seen approaching the two nails in the lower cork. The upper right photograph shows the explosion just starting. The lower and upper corks are still intact and the explosion is apparently pushing out around an opening between the glass tubing and the lower cork. The lower left photograph is one frame later (0.033 sec), and the lower right is several frames later still. It appears to us, that performing the octane cannon experiment in this fashion shows fast reactions in a different way and can lead into many interesting topics such as intermediates in reactions, adiabatic processes, shock waves, and and lower limits to fast reactions. Alyea, H. N., "Tested Overhead Projection Series in General Chemistry." 2nd Ed., Chemical Educational Publishing Company, 1965, p. 26.
A.H. Richtol Rensselaer Polytechnic Institute Troy, New York 12181
856 /Journal of Chemical Education
D. L. Nelson R. R. Reeves
