X800: Combustion – The Non-Burning Towel
Introduction
A small laboratory towel is dipped in a mixture of alcohol and water and ignited. After several seconds the flames are extinguished and the towel appears unharmed by the fire.
2C3H7OH(l) + 9O2(g) —> 6CO2(g) + 8H2O(g)
To Conduct Demonstration
- Using crucible tongs, dip a lab towel into a beaker containing a 50/50 mixture of isopropyl alcohol and water. Excess liquid may be squeezed out of the towel for a shorter demonstration, although any alcohol that gets on hands or clothing should be rinsed and dried before proceeding.
- Hold the towel out with the tongs and light with a butane lighter or candle.
- Allow the alcohol in the towel to burn until the flames begin to die down. Extinguish the flames with a rapid up-and-down jerk of the towel. If the flames don't go out immediately, simply repeat this motion after a few seconds. The alcohol should be consumed and the towel should be cool and dry to the touch.
- The combustion may also be done with money (bills) or other paper. It is popular to ask someone from the audience to volunteer a bill for the demonstration.
Demo Time: ~5 - 10minutes
Safety
Keep open alcohol away from any flames (except the ones in the demo!).
Reference:
B.Z. Shakhashiri, Chemical Demonstrations: A Handbook for Teachers of Chemistry, Vol. 1, 1983.