Ping Pong Fireballs


You probably know that one of the best ways to fight fire is with fire -- if you carefully burn an area ahead of a fire, then when it gets there it can't burn any further. But did you know that the forest service uses ping pong balls to start controlled fires? In an airplane or helicopter, a firefighter injects a clear liquid into a small hole in a ping pong ball containing a purple solid. Nothing happens at first, and the firefighter tosses the ball to the ground. After a few seconds, it bursts into an intense flame.


This is a reaction known as "delayed fire." The purple solid in the ping pong ball is potassium permanganate (KMnO4), and the clear liquid is glycerine (C3H8O3). When the two substances are combined, nothing happens at first, but after a few seconds the mixture starts to boil and smoke, and then bursts into an intense flame.

4C3H8O3 + 14KMnO47K2CO3 + 7 Mn2O3 + 5CO2 + 16H2O + heat

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explanation furnished by UCCS's Dr. David Anderson