Hydrogen Balloons

Hydrogen balloons are spectacular. I like to show the students the synthesis of water molecules at a slow rate and a fast rate. A pure hydrogen balloon will burn relatively slowly because only those hydrogen molecules that have moved out from the balloon and mix with oxygen in the air will be able to react. This leads to a large flame with little noise. We videotaped the action and used a frame-by-frame VCR and a Snappy video capture device to obtain still images of the action. Watching the tape at regular speed, only a quick burst of flame can be seen. When slowed down, one can see a series of reaction images.

H2Balloon3.jpg (4832 bytes)


I also like to do a pre-mix balloon where hydrogen is put in the balloon first and then oxygen is added as well. Upon ignition, this balloon will react much faster because the hydrogen molecules are already exposed to their reaction partners. Watching the videotape at regular speed, one sees a balloon followed by no balloon. Only when you slow things down do you really see the action. The flame from a pre-mix balloon is very quick, but it produces considerably more sound than the non-mixed balloon.
If you've made it this far, you deserve to see a larger water synthesis: the hydrogen weather balloon (40 K)

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