An odd, and off topic, question...

It's not MAD science...just disappointed.

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Postby BenTGaidin on Mon Sep 25, 2000 7:27 am

I thought I'd ask here anyway, because this seems like a sharp bunch of people. <IMG SRC=""><P>Would it be possible to freeze soap bubbles, if you got it cold enough, quickly enough? I'd think it would be possible, but I'm not sure... And if it is, does anyone have a good suggestion for how to do so?<P>Also, would it still float? (Assuming you freeze one that's in air) My mental picture has it dropping and smashing, but I can't think why it should... It wouldn't change mass and I don't think rigidity would make any difference... And I can't decide in which direction it's density would change, if it did.<P>Ah, well. I don't know if anyone would know the answers, but it's just one of the odd questions that came to mind tonight.<P><P>------------------
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Postby Ydracth on Tue Sep 26, 2000 2:24 am

Wiigii! Off-topic topics are the way to greatness, or at least to being like the CRFH forum. <IMG SRC=""> Frozen soap bubbles are the way to something too, but what has not been revealed to me.<P>The first problem is the pressure drop as the air in the bubble cools. That can be fixed by adding more air, or by cooling the bubble in an airtight container so the pressure drops evenly inside and out. (Actually, that wouldn't work since the outside would cool faster and the bubble would burst.) Dropping the pressure might be a bad idea anyway - we want the bubble to freeze, not evaporate.<P>Next problem: surface tension is what holds the bubble together, and a frozen bubble won't have any. A frozen bubble will also lack the springiness of the soap film, so it will have to be much stronger. A layer of ice that thickness would probably be too weak to support even its own weight. So I guess freezing ordinary bubbles won't work. (Unless they can be handled really delicately in zero-G.)<P>Ways around this:
<LI> Make the walls thicker than an ordinary soap film. A lot thicker. Try adding extra water as the bubble freezes, or even freezing an underwater bubble. (Soap optional.)
<LI> Add something to make the ice tougher. (Some sort of water-soluble polymer? Or something that adheres to ice crystals?)
<LI> Abandon ice and use something else (glass or plastic) that's stronger. But that's not exactly new, and it's cheating anyway.
</UL><P>Some other things:
<LI> The soap and water might separate as they freeze. I have no idea to what extent this might be a problem.
<LI> Ice crystals will tend to grow rather than freeze in a film. Appropriate soap additives might help with this. So would very fast cooling.
<LI> The bubble could be build around a balloon (which can be considered a kind of frozen bubble) which is removed when done.
<LI> Making a naturally thick soap film would be a big help. Is there a ChemE in the house?
</UL><P><I>thinking of fun ways to destroy frozen bubbles</I>
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Postby chemcat on Tue Sep 26, 2000 4:36 am

You're thinking too hard...I've seen basic soap bubbles frozen in simple liquid nitrogen. as far as will they float and what not: your problem is not with density. if you're freezing it in water the thin skin will almost instantly melt causing a pretty ugly bubble. but it was floating in the nitrogen if memory serves...
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Postby LCARS on Tue Sep 26, 2000 6:24 am

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by chemcat:
<B>You're thinking too hard...I've seen basic soap bubbles frozen in simple liquid nitrogen. as far as will they float and what not: your problem is not with density. if you're freezing it in water the thin skin will almost instantly melt causing a pretty ugly bubble. but it was floating in the nitrogen if memory serves...</B><HR></BLOCKQUOTE><P>
I've seen that on Letterman before.
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Postby magenta on Tue Sep 26, 2000 7:13 am

I used to work at the Albuquerque Children's Museum.<P>I bring this up because one of the first exhibits ever to be there was a soap bubble freezing device. They only had it up for special occasions (it was expensive to run), but it was still very neat when it was.<P>Basically there was a big block of dry ice in a closed-off chamber (made of plexiglas), and a fan, and a thingy you could dip into soap solution which would put a film of soapwater in front of the fan. You know, a typical bubble-making machine thingy. (That's the technical term.)<P>The air, being quite cold (from the dry ice), caused the soap bubbles to freeze quite rapidly. They still floated (of course - the mass, density, and displacement didn't change), and they'd gracefully fall down, down, down, and land on the block of dry ice, where they'd basically be crushed under their own weight (not much weight, but not much strength either) - the bottom would freeze to be even stronger (from being in direct contact with the dry ice), and the top would deflate into a little concave-up half-shell of frozen soap film. From there they'd (very slowly) sublimate along with the dry ice.<P>It looked pretty cool. I wish I had pictures, since I know it doesn't sound very believable from this description.<P>------------------
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Postby AndyL on Thu Sep 28, 2000 12:08 am

Why not try it? You can get interesting results with just a freezer. <P>Make a medium sized bubble and land it back on the (wet) bubble-wand. <P>The put it in the freezer. MAke sure it's sheltered from the fans.<P>I've never actualy gotten one to stay intact. I think once they freeze they collapse under theier own weight. But you can tell they were bubbles. They're thin and pieces of them are still the right shape.<P>-Andy
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