Subject: Bunsen Burner Cool Zone
At the beginning of the year I have my students perform a lab activity in which they learn how to properly light a Bunsen burner and adjust the air ports to change the flame from luminous to non-luminous. For some of my students it is their first time lighting a match.
In addition to using the burner, I attempt to teach them where the hottest and coolest parts of a non-luminous flame are. This information will be needed to perform certain lab activities later in the year. In the past, after questioning the class I would make a general announcement describing the location of the two zones. I would then follow that up with a visit to each lab station and attempt to point out the zones with some object, such as crucible tongs or a glass stir rod. However, throughout the year they would forget and try to heat items by placing them in the coolest part of the flame.
Upon looking through an old lab manual* left behind by one of my predecessors, I found a figure which pictured a match placed down the barrel of a Bunsen burner, held in place with a straight pin. I decided this year to try performing this demonstration for my students at their lab stations with the hope that they might see and remember.
When I performed this demonstration, I definitely had the attention of my students. The sight of a match sitting in a lit burner flame and not igniting perplexed them. This was a teachable moment. I don't know whether or not they will remember the hot and cool zones later this year, but if they forget I will be able to draw upon this activity and have them recall a picture.
I hope this information proves useful in helping you reach a few more students, and that you enjoy using it as much as I do. If you have any comments or suggestions, please feel free to contact me.
* Tellefsen, Robert L., Dietz, Phyllis M., Parry, Robert W., and Steiner, Luke E., Laboratory Manual Chemistry: Experimental Foundations. New Jersey: Prentice Hall, Inc., 1970, Appendix A, pg. 125, Fig. A2-3.
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Deer Park High School, Cincinnati, OH