The Thermite Reaction
****DISCLAIMER****This is an experiment that produces extremely high temperatures and so definitely should not be attempted without the assistance of a qualified science teacher or technician. St John's does not take any responsibility for accidents resulting from this experiment.
Method
Iron oxide and aluminium powder were carefully mixed together. The mixture was then poured into a pair of fluted filter papers which were then supported by a pipe-clay triangle and tripod over a 2l beaker filled with a layer of sand and then water. A small depression was made in the centre of the thermite mixture. Into this depression an igniter mixture formed from magnesium powder and barium nitrate was placed. Finally a strip of magnesium was pushed into the igniter mixture. The tripod and beaker stood on heatproof mats and all the apparatus was surrounded with safety screens. Observers wore protective filtered goggles and stood at least 3m from the demonstration. The magnesium strip was lit with a roaring bunsen flame.
Results
Conclusion
The thermite reaction is an example of a displacement reaction. This spectacular reaction occurs because aluminium is more reactive than iron. The aluminium displaces the iron from iron oxide. Thus, aluminium oxide is formed whilst the molten iron is produced. The molten iron produces the orange sparks that are observed. Lumps of iron can also be found in the sand water mixture after the reaction is completed. They can be easily retrieved by using a magnet. Since molten iron is produced this reaction has been used in the railway construction industry in order to weld lengths of rail together.