Thermite
GCSE chemistry is as dull as ditchwater. You've got a class full of budding young pyromaniacs, terrorists and druggists, and most of the syllabus involves 'fun' things to do with copper sulphate and iron wool.

The only real high point as far as the kiddies are concerned is the redox reaction that is THERMITE! Every class will have heard about this fun experiment from the years above and will be begging to try it out the moment they walk though the doors of their first lesson. I've no idea if schools are still allowed to demonstrate the fun that is thermite, or if they just show a video or two from youtube, but when I were a lad, my school decided to do something different for our demo.

Rather than have the various science teachers do individual demos before a class of 30 or so, it was decided to do one big demo for the whole year. Thermite day arrives and we are led out onto the back field. The rather damp and muddy back field.

The thermite is set up in an old clay flowerpot on top of a couple of blocks on a patch of sand on mud. A hundred or so youngsters watch as the magnesium strip poked in the pot is lit and the teacher runs away from the proto-inferno. A few seconds later and the scene whites out. Vision returns and we can see flames & smoke & sparks. The pyromaniacs and terrorists are making comprehensive notes, the druggists are wondering if this gets them any closer to making E from the content of their bathroom cabinet.

The reaction dies down and the cheering starts. Then the flower pot cracks spewing bright orange molten iron all over the bricks and sand and OH-FUCK! mud!

There is a bang. Nope, there is a loud BANG. Or even a *FUCKING LOUD BANG* followed by a lot of small sizzles.

The hot iron hitting the damp mud made a steam explosion which scattered iron, bricks, pot and thermite. All sizzling and steaming where it landed.

It is as close a thing to a miracle as an atheist like me can believe, not a single person was hurt.

The school returned to small individual demos after that.
( speedyballbangpots, Tue 3 Feb 2009, 12:27, 2 replies)

Nice
Apparently a dollop of said chemicals on a car bonnet will melt straight through and make a bit of a mess of the engine block. A bit more dramatic than sugar in the petrol tank.
( monkeybananaraffle, Tue 3 Feb 2009, 13:39, closed)

Excellent
Reading around this subject on Wikipedia has taught me the new word Phreatomagmatic, which I shall attempt to inject into conversations from now on.
(ragged, Tue 3 Feb 2009, 13:59, closed)