Thermit Video

Thermit

The thermit reaction is a great reaction to show the kids. A simple single displacement reaction takes place between aluminum and iron (iii) oxide to form iron and alumina. Specifically, it is a competition reaction. Aluminum, the more reactive metal, displaces the iron, the less reactive metal. What makes this reaction special is that all of the reactants are in the solid state (not something you see all too often). However, do not fret. Mixing the two reagents together yields no reaction. The activation energy, the energy required to start a reaction, needs to be overcome. An easy way to do this is to use yet another metal, magnesium. I cut a piece of magnesium ribbon about 9cm long and frayed one of the ends. I did that because anyone who has taken kinetics knows that one way to increase the rate of a reaction is to increase the surface area. So, I light a splint which I use to light the ribbon. The magnesium burns intensely and once it reaches the thermit mixture it ignites it and starts the reaction. Sparks fly and the heat can be felt from a few feet away. The reaction is so hot that it is used to weld railway ties together.



Kids love this stuff.