Subject: CD Burner Demonstration
A CD appears to erupt in flames and burn for about a minute.
- combustion reactions
- exothermic reactions
- oxidation of an alkane
Elmer's rubber cement (contains n-hexane)
lighter or matches
I begin this demonstration by asking my students who has their own computer. Of those students who have their hand up, I ask which also have a CD burner with their computer. The responses vary from one class to another, of course. I then ask which students wish they had a CD burner with their computer. I always get at least a few students who raise their hands. At this point I tell them that they can make their own CD burner for very little money. While telling them about my new "discovery" I open up the jar of rubber cement and liberally cover about half of the CD with it. After closing the rubber cement cover, I light the CD while holding it with the crucible tongs. At this point the students realize the joke and let out a few groans. I discuss the reaction while allowing it to burn itself out (about 1 minute) before setting it down to cool. (I usually add a joke about making sure not to place the CD in the CD drawer while it is "burning" or it might interrupt the file creation process; more groans.)
After the demo has finished I point out to the students the structure of n-heptane and we discuss what products were made during this reaction then balance the chemical equation. It makes for a good demo-a-day and allows for an introduction to or review of combustion reactions, or could be used to demonstrate the oxidation of alkanes in organic chemistry.
In this reaction the n-heptane (the solvent for the cement) burns off of the CD without causing the CD to burn (the CD will begin to melt).
A balanced equation for the reaction is: C7H16 + 11 O2 ---> 7 CO2 + 8 H2O
This activity has potential hazards which need to be evaluated. The reaction can produce smoke, and the burning rubber cement does pop and sputter. Perform this demo over a flame proof substance such as sheet metal or sand. As with all demonstrations, never perform a demonstration for the first time in front of students. Practice it first. Moreover, when performing this or any demo, use common sense and wear protective safety gear!
|DISCLAIMER OF LIABILITY: This page contains information about a demonstration which is potentially dangerous. The
Catalyst assumes no legal liability or responsibility for the use or misuse of the information
contained on this page.
By accessing this page you understand and agree to release The Catalyst and its author of any liability. If you do not wish to agree to this, please leave this page immediately!
Michael Geyer (email@example.com)
Deer Park High School, Cincinnati, OH<