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Hydrogen Balloons

This is a revision from April 21, 2012 14:48. View all revisions
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Hydrogen generation test at NuVuWorkshop

Hydrogen generation setup

Here's our basic setup, just to measure hydrogen volume output. Aluminum and lye (in water) are mixed in the test tube, hydrogen is pushed out the tube into the bottom of the flask on the left. The flask is filled with water so it cools any water vapor (the reaction is exothermic and produces steam) so that the balloon is filled only with hydrogen (plus a little air that was in the system already).

Safety officer


Lye is caustic and quite dangerous if exposed to skin or eyes. If you touch it, flush with water then vinegar or another weak acid. Use rubber gloves and eye protection.

Scraping plastic off the aluminum can

Aluminum cans are coated in plastic, so to get things going you can scrape it off with scissors or a knife.

Aluminum beginning to bubble

We dropped in some aluminum and stoppered the test tube. It began bubbling a bit immediately.


Hydrogen coming out in the bubbler.

Aluminum bubbling in lye

Here the reaction is really going strong. Our exit tube was too narrow and the stopper popped off from the built-up pressure. Exciting.

Corrected hydrogen generation calculations

Here's our calculation (illegible) of how many grams of aluminum produce enough hydrogen to fill a 5-foot balloon (sphere). I think this is wrong; we assumed Al2, not Al.

We calculated 33.8 aluminum cans (at 13.6 grams each). We didn't get to confirm the result.