Content area
Full Text
The reaction of aluminum with the oxides of a variety of elements-aluminothermy, or the Goldschmidt processillustrates exothermic reactions that require a high activation energy. It is also an appropriate experiment for introducing Ellingham diagrams. Because of its spectacular nature, this reaction is a favorite for demonstrations, and a number of articles on ways to initiate and conduct the thermite reaction have been published in this Journal (1-11).
When a spectacular show is not the main objective, these reactions may be conducted on a microscale level, as described below, with numerous advantages over the usual scale (20100 g of Al-MOx mixture). These include:
1. The hazards are insignificant so that the usual protective shields are unnecessary. The reaction can be observed at short distance and conducted simultaneously by several students without special oversight.
2. Sparks and fumes are easily controlled so that hoods, though convenient, are not required.
3. Crucibles used to contain the mixture can be reused.
4. Work-up is facilitated and substantial time is saved, especially in handling the reaction products and cleaning or protecting the installations. The entire procedure is completed in less than 1 hour so that instruction and discussion before or after lab are possible in a normal 3-hour session.
Procedure
An intimate mixture of 0.9 g of dry Fe203 and 0.3 g of dry, finely powdered Al is placed in a small conel of common paper.2 The cone is placed in the center of a crucible 4-6 cm in diameter, which is filled to approximately 1 cm from the top with...