The thermite reaction

The thermite reaction is very useful, and very fun. I've seen it used for spot welding during the construction of our local tram here in Dublin, and I've also seen it explode powerfully late at night in a remote part of the Dublin mountains.

Thermite reactions are classic examples of oxidation / reduction. One metal is burned and another is reduced to its elemental state. The traditional reaction is: $$Fe_2O_3 + 2Al \to 2Fe + Al_2O_3.$$

In early 2009 I gathered a few friends and made a couple of trips up the Dublin mountains where we carefully experimented with thermite. We tried each of iron, copper, and manganese thermites and we successfully ignited them with a magnesium fuse, as well as via the glycerol and potassium permanganate reaction.

Safety first

The intention of these trips was to have a little fun, in the spirit of fireworks, but they also provided a valuable unexpected lesson: safety first. We were very careful and I recall thinking we might have been taking ourselves a bit too seriously. As it turns out the copper thermite reactions exploded powerfully, rather than burning as expected.

Fortunately all was well as we always ensured we were far away at ignition time. We watched from a distance as it literally rained molten copper.

Some videos

Copper thermite explostion (video)
Standard iron thermite reaction (video)
Unfortunately I had to mute these for the sake of others' privacy so you cannot enjoy the satisfying boom.

Some photos