Saturday, February 24, 2007

Blessings from 2/18-2/24

  1. Survived a thermite reaction (more about that below)
  2. Beautiful weather for much of the week
  3. Early dismiss yesterday for work afternoon - got much done
  4. Got in exercise 3 days this week
  5. Stayed OP, even if the scale didn't move much this week

OK - the thermite reaction. Tom decided a couple months ago that he wanted to show the kids a thermite reaction in class. A thermite reaction is what some experts think was used to bring down the twin towers. Yeah, a little nervous-making. For a more practical application, a thermite reaction extracts native iron (pig iron) from hematite (rust, basically). Since we talk about ores and such in Earth Science, it has relevance (barely). He presented his request to administration, and made them very twitchy. Eventually, they gave permission, and we were on 'Go' for Thursday.

How it works: Thermite is a mixture of hematite (powdered rust) and aluminum powder. Hematite isn't scary, aluminum powder is. This stuff ignites when exposed to water. So, get some in your eye? Inhale a little too much dust as you pour the powder? Not a good idea...

Anyway, you mix the hematite and aluminum, and put the mixture in a small clay flowerpot (hole covered in the bottom). Put that flowerpot in another flowerpot, and suspend both in a ring stand. Stick a sparkler in the thermite for a fuse. Fill a coffee can with dry sand, and place under the suspended pots. Light the sparkler, and run like hell.

What happens? Well, the sparkler ignites the thermite, which sets off the reaction. This reaction generates heat in excess of 2500 degrees F! As you watch this fireball, you can see molten material flowing out of the hole in the bottom of the second flowerpot, in to the coffee can filled with sand. Soon, the coffee can is glowing. When the reaction is over (about 2 minutes for this amount of thermite), you can see a white-hot lump of molten iron resting in the sand. When it cools, you have a lump of pig iron! Needless to say, nothing is left of the hematite and aluminum mixture, and the container flowerpot is ash.

Really neat, huh? Things went like clockwork 2nd period - everyone behaved, stayed back behind the marked line, the sparkler lit without incident. Yay! Fast-forward to 7th period...

All day, the wind was getting stronger. By 7th period, we had gusts up to 30 mph. Hard to light a sparkler in the wind. Tom enlisted my help - I had a large piece of cardboard to hold up beside his weapon of mass destruction to help block the wind. He decided to light another sparkler in the building, and use it to light the sparkler in the thermite. OK - let's look at that word "sparkler." Notice anything? Yeah, as he was trying to light the sparkler in the thermite, a spark ignited the reaction! I don't think I've ever run so fast in my life.

Don't try this at home...

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