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

  1. 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.
  2. Hold the towel out with the tongs and light with a butane lighter or candle.
  3. 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.
  4. 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.