Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: kctabby on March 25, 2005, 09:46:11 AM
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My probem is that I was given an assingment to create a working hot air balloon without using a flame and by using household materials. I have been researching for a few days now and have come up with limited solutions. One is the use of hydrogen peroxide and lead at a certain concentration. However, I have been unable to produce a pressure great enough to lift a 3 to 5 lb. hot air balloon frame. Any suggestions??
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Well, you could go on the principle that hot air balloons use, and that is to generate heat in such a fashion that you change the air density inside the balloon. You might want to look at how that's done on the web. If you can use this, then I'd get a few small glow coils (resistive heaters) from Radio Shack or some other electronics store, and you might be able to plug it into the wall and heat it. Unfortunately, that produces risk of fire and also of shock because of an exposed coil.
I would also suggest filing the balloon with helium, but that is a problem because you don't have it in your house.
Next suggestion would be to fill the balloon with hydrogen, but I don't really like that idea much. I think it's a little irresponsible to have your students figure out how to generate hydrogen from household materials, as it will inevitably lead them to the internet, where lord only knows the quality of information available. Besides, that's not how hot air balloons work--it's how the Zeppelin worked, but not a hot air balloon. You've also got the problem of the hydrogen being flammable. I'd be careful if you're putting it into a plastic bag because of static.
3-5lbs. is a LOT of weight to be lifting. How big is this thing?
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I gave bad information. The balloon frame weighs about two pounds from the wire shell to the basket below. The three to five pounds was including the materials I attempted to use. (lead + hydrogen peroxide). I have looked up hot air balloons and how they work but like I said, my problem is my inability to use fire. Maybe there is a way to protect the basket from the core if used?
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You don't need to use lead to decompose H2O2. Something as simple as a little bit of ground beef will cause hydrogen peroxide to exothermically decompose into oxygen gas and water.
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5lbs is about 2.3kg. One way of providing heat (using household materials) is by setting up an electrochemical cell (similar to the daniel cell). Drawing electrical energy from household chemicals to provide for heat should be plausible.
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My question is: can you reasonably generate enough heat using electrochemical or simple exothermic reaction methods? I think you need a LARGE increase in temperature in order to make the air of a significantly low density to raise a 5 lb. balloon. This is just by intuition/a feel for it. Think of helium. It has a much lower density than air at RT, and you'd need a LOT of helium-filled balloons to lift a 5-lb. balloon/basket/whatever off the ground. Even if you filled a trash bag with helium (assuming it didn't diffuse out), you'd have trouble lifting a 5-lb. weight I'd imagine. Even if this thing is 2-3lbs, are you really going to be heating up air hot enough to lift even a 2-lb. object from the floor? I have my doubts. If you're using fire, then OK, you can raise the temperature quickly, although I think that it might still be a challenge.