I braved my son's 3rd grade classroom this week and brought in some dry ice and liquid N2 demos to couple with their science unit on solids, liquids, and gases. The kids LOVED it! And 3rd graders are such a cheap thrill after cynical college students.
Me: So what do you think is going to happen when I put this balloon in the liquid N2?
Kids: IT'S GONNA EXXXXPLOOOOOOOOOOOOODE!!!!!!! (all of them covering their ears)
While hunting around quickly on the web for some info, I found this neat liquid nitrogen demo script from a Physics Demos for Kids site at UCSB (for more examples, click on Demo scripts under Program Information on the left side).
Does anybody know of any similar programs with online demo scripts for Chemistry? It seems like this would really lower the bar to help me and my students get into the K-12 classrooms, not to mention work with Girl Scouts, Boy Scouts, and other groups.
Good job with this. I have used the liquid nitrogen for solids/liquids/gases for some time now and found it great. To expand on this, bring in some dry ice (solid/gas). Put some in the bottom of a test tube (large tube), and ask kids what it is. Talk about it for a minute. Then, put a balloon on top of the tube. Ask them why it blows up (what gas is inside the balloon). You can go on with this for some time.
If you use clearish balloons (ones you can see through, not necessarily colorless), the next part is really cool. Pour some liquid nitrogen into a small dog dish (that's what I use, whatever you have will work). Put the CO2 filled balloon into the liquid nitrogen. The balloon will essentially become flat. The interesting part is, the CO2 forms back into a solid, and so the kids can see that. You have to talk about it and convince them that that is what is inside the balloon. As the balloon re-expands, the CO2 obviously goes from the solid to the gas. You can go on and on with this for quite some time, talking about solids/liquids/gases. It's a great demo.
A new note on this: The last time I did this, I didn't tie up the balloon. I simply left it on the end of the test tube and froze it there. Then, when the solid formed, I let it "rain" back into the test tube. They could see it then. It was impressive.
In the end, I always make liquid nitrogen ice cream, but the marshmallows sound good as well.
Keep at it, I have all sorts of experiments that I do with kids in our town (we live in a rural community, so any outreach with the kids is greatly appreciated). I try to tie it with their lessons, but you can do a whole lot of experiments that relate to what they are doing. I use the above experiment for solids/liquids/gases, but I also use it when talking about the water cycle (though CO2 is stretching it, it's the same general concepts).
Let me know if you have any questions. I have been doing this outreach in our community for over 10 years now, and so I've built up a few that work really well.
Good luck.
Dave
To follow on this theme, we pour some liquid nitrogen in a fairly thin, metal wok and hold it up to watch the liquid oxygen condense and drip off the bottom. You can drip some on some cotton and (carefully, from a distance) light the cotton on fire to show that the oxygen supports combustion. Again, following this theme, if you blow up a balloon and freeze it in liquid nitrogen, you can see some liquid oxygen inside the balloon. This would be cool done side-by-side with Dave's dry ice balloon.
And never underestimate the fun of letting kids put dry ice in balloons (a plastic funnel helps with this), tie them off, and watch them expand. "Will it EXXXPPPLLLOOODDDEEE?"
Finally, never never never forget to make everyone wear safety glasses.
In reply to demos for kids by Dave Roberts / DePauw University
http://www.depauw.edu/learn/scienceforkids