Spontaneous Generation 3

Purpose:

The addition of a small amount of warm glycerol to a pile of potassium permanganate will result in spontaneous combustion. White smoke and a purple flame will be seen. You will need to wear goggles, chemical apron, and gloves.

Materials:

• 5 ml glycerol (warm)

  2 evaporating dishes

  mortar and pestle

  10-20 g of potassium permanganate (KMnO₄)

  2 eyedroppers

  spatula

Procedure:

1. Place 5 g of potassium permanganate (KMnO₄) directly from the jar on the evaporating dish.

   Grind 5 g of potassium permanganate (KMnO₄) to a fine powder and place on the other evaporating dish.

   Form a depression in the center of the potassium permanganate for the glycerol.

   Using the 2 droppers at the same time, add glycerol to the depressions and step back.

   Disposal is down the drain with small amounts of waste being added to large amounts of water while you are wearing your safety equipment.

Discussion:

This demonstration starts off slowly and then speeds up as the glycerol oxidation produces heat. Using two piles of potassium permanganate allows us to see the effect of surface area or particle size on a chemical reaction. If the glycerol is cold the reaction does not appear to work.

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