The new thermite reaction

20 June 2012 - Fool around with chemicals

It is time to fool around with chemicals. The Journal of Chemical Education regularly publishes about igniting stuff, a long tradition dating back to 1930. In a recent issue McGuire et al have another look at the thermite reaction (DOI) of iron oxide and aluminium. The hazards section reads: "an outdoor setting is preferable" and "observers should be situated well back from the reactions, at least 15 or 20 feet from the estimated extent of the reaction". This is going to be good. The reaction of Fe2O3 and Al mixed together to form elemental iron (molten!) and Al2O3 is exothermic but requires a serious kick-start. The authors heartedly suggest a mixture of potassium perchlorate and sugar to be added to the mix. A few drops of sulfuric acid will set the fireworks in motion. As the authors explain sulfuric acid and KClO3 initially react to form KClO3 and K2SO4, the KClO3 then oxidizes sugar in a reaction that generates sufficient heat to decompose the bulk of the KClO3 to KCl and oxygen. Sugar and oxygen then provide all the energy to get the thermite reaction started.

Movie time!