Discussion

The thermite reaction involves a mixture of iron oxide and aluminum that has been placed in a flower pot and covered with potassium permanganate. Some glycerin is poured over the potassium permanganate and eventually begins to react. When the iron oxide-aluminum mixture is ignited, a very vigorous reaction occurs and a molten metal can be seen dropping from the flower pot into a bucket of sand below. The reaction is extremely exothermic, a great deal of heat is given off. When the product of the reaction is examined a large piece of white hot iron has fallen into the sand at the bottom of the apparatus. This illustrates that aluminum is an extremely strong reducing agent and also that this reaction is very highly exothermic.

The equation for the thermite reaction is:

Fe₂O₃ + 2Al → Al₂O₃ + 2Fe

The equation for the glycerin with potassium permanganate reaction is:

14KMnO₄ + 4C₃H₅(OH)₃ → 7K₂CO₃ + 7Mn₂O₃ + 5CO₂ + 16H₂O

The mixture of iron oxide and aluminum is placed in a doubled flower pot, with a small folded section of paper towel placed between the two pots to prevent the reactants from falling through the pot drainage holes. The pots are placed in a ring stand, about 80 cm above a large metal crucible (iron pot) 3/4 full of sand. The reaction requires heat energy to overcome its reaction barrier, and in this demonstration the energy is supplied by way of a magnesium igniter that is lit with a Bunsen burner. The igniter is lit, sending off hot sparks as it burns, and thrust into the mixture of iron oxide and aluminum. The reaction begins, releasing copious energy in the form of light, heat, and some sound, as the newly liquefied iron/aluminum oxide mixture flows through the pots into the crucible below. This reaction also produces a large amounts of smoke, some of it from the paper barrier between the two ceramic pots.

This reaction was videotaped without an intervening barrier for purpose of clarity. This reaction is very dangerous, and all safety precautions must be followed.