High Flying Science

High Flying Science-1

Redo hydrogen and Helium-filled ballons

In 2001, Stephen Donnelly filled balloons and brought them to the MSR for us. This year, Verity Stroud will email Stephen and ask for detailed instructions.

  1. Party-size, He-quality balloon with hydrogen in it - gives a good bang

2H2(g) + O2(g) = 2H2O(g) -analogy of bowling ball at top of hill - activation energy

Salts: Use chem spatula to put ~1 gram in each balloon. Then fill with Hydrogen.

WEAR GOGGLES, spray clothes with static guard before handling balloons.

The salts spray everywhere. Coarser salts will sting if hit you. We did not notice anyone being hit in 2001.

Tie balloons 3' from ceiling and walls (or more). Fill balloons 1 hour before show or less so small molecules don't have time to diffuse through rubber.\

Can see fine in daylight but more spectacular with the lights dimmed.

We need to have Melinda Powers in the loop each time we do this demo. I think in 2003 we had a silicon glass blanket on the floor to snuff out fires. I think we borrowed it from the welders shop.

  1. Gigantic balloon with helium - no explosion, but kids see huge balloon and expect a huge bang.

This is just as a contrast. H2 explodes He does not.

Here's the original email from Toni Prenni, a postdoc at CSU back in 2001

Date: Tue, 2 Oct 2001 17:37:47 -0600 (MDT) From: Tony Prenni <tony@aerosol.atmos.colostate.edu> To: Janine Goldstein <janine@joss.ucar.edu> Subject: Re: Exploding/flaming bubbles and balloons

Sure, I can tell you what I know. Are you just interested in exploding balloons or do you want information on other demo's as well? I can meet with you if you like, or I can just tell you via email.

As far as the balloons, I usually do a total of four balloons in the following order:

1st: A small/mid-sized balloon with only oxygen - it gives off a nice flame, but doesn't really explode.

2nd: A small/mid-sized balloon with only hydrogen - it gives off a pretty good bang. The reaction is 2H2 + O2 --> 2H2O. However, the reaction is limited by how quickly oxygen (from the air) can diffuse/mix with the hydrogen to make the reaction happen.

3rd: A small/mid-sized balloon with a mixture of 2:1 hydrogen:oxygen. With the appropriate stoichiometry - this thing gives off a BIG BANG!!! (Note from Melinda: Don't do this in the Main Seminar Room - ceilings are too low, room is too small, ...)

4th: A gigantic balloon with helium. Of course, helium doesn't ignite, but the kids see that you've got a larger balloon and expect an enormous bang - the anticipation is worth it.

Procedure: Tie the balloons to a string, and the tie the string to a railing at least 10 feet from any people....maybe 15-20 ft. Also, be sure to keep the balloons separated when lighting them! You then tie a candle to a long rod (again, maybe 15 feet if you can find something that long) and ignite the balloon from a distance! There's no need to be anywhere near the balloon when it explodes. I usually let volunteers ignite it.

Of course, goggles are a must, and , depending on the age of the students, I would warn them that you're going to make a loud bang so that they can cover their ears if they like.

Finally (during prep) when filling the balloon with hydrogen/oxygen, be sure that (1) there are no flames nearby, and (2) you're not wearing clothes that cause alot of static. A little shock can make a large explosion!!! This happened to a graduate student about 4 years ago, so be careful!

I think that's it. Let me know if you want more info. Good Luck! Tony

SuperScienceSaturday: SuperScienceSaturday2003 (last edited 2010-01-21 02:50:55 by localhost)