Smug Git
Arrogance Personified
Registered: Aug 2001
Location: Hilbert Space
Posts: 35561 |
It is a very good idea to get qualified as a chemistry teacher simply for the amusement value of blowing stuff up.
I have seen a video (maybe the one that rosh referred to) where caesium is put into water and there is an explosion, that looked pretty cool.
Interestingly, the horriblest chemical that I used was as a physics teacher rather than in teaching chemistry; bromine is nasty stuff (apparently it burns inside your skin or something nasty like that) and I try to avoid using it (not bromine water, which is often used in lieu of bromine in experiements because it is safe).
Used to do some cool demonstrations with a 50:1 mains step-up transformer; 12 000V is pretty scary stuff (not like the higher, but safe, voltages produced by a lab Van de Graaf generator, this stuff was the real deal). We used to put two long terminals coming out of the transformer, about 1/3" apart at the bottom and getting to be maybe 5" apart at the top. You get the cool rising spark effect like in the Frankenstein movies (the spark starts at the bottom where the voltage is big enough to drive a current even through the air, then it heats a surrounding channel of air to a plasma, which is a conductor (unlike air) and glows. This hot plasma rises (hot gases rise, and plasma is basically a charged gas); the spark follows the conducting channel of plasma, which keeps it heated and glowing and so it goes to the top of the terminals before the plasma drifts too far up and then cools down due to lack of continued current), but it would be dangerous to be too near (the kids were on the other side of the safety screen and at least 10 feet away from the screen, even).
We has another demonstration with a 6000V military capacitor; using that, we could use the safe eht supply ('extra high tension' - about 5000V but with a 50 Mega Ohm internal resistance, which makes it incapable of delivering a high enough current throught the terminals to be dangerous) to slowly charge it; it would be connected in parallel to a pair of large foil plates separated by plastic bags. We turn off the lights and the plates would charge from the capacitor until they blew holes through the plastic bags, which was pleasant to watch (like fireworks indoors). This was also dangerous to be near (not as bad as the other one, but dangerous enough; dead is dead). Before the military capacitor was found, they had to make a leyden jar from dustbins (also dangerous) to do the demonstration.
We used to do fun demonstration experiments every Christmas; most the kids could do themselves (like boiling water in a hand-made paper saucepan, which always amazes kids for some reason) but those ones above were by demonstration only.
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10-08-2002 02:51 AM
His site wont load for me.
