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RE: Whats in Helium?



Here's my ideas...
I am a chemistry major here at my university so hopefully this is clear!

 you aren't converting Helium to other gases. What is happening is there is
a high (well, maybe not high in Bob's "watered down" Helium ;-))
concentration of Helium in the ballon which is a semipermeable membrane to
us chemists. That creates a concentration gradient across the balloon.
Since there is a lower concentration of helium in the outside air...the
helium seeps out seeking equilibrium.
My guess is that your helium was "aired down" so that when the helium
osmosed out of the balloon you still have the regular air in the ballon
minus the helium. And since the concentration of the regular air in the
balloon is the same as outside the balloon...it won't try to
equalize...thus you have the 2/3's full balloon and Zero lift!

My .02 cents worth!
Jamie, KD5GOB



At 05:36 PM 03/10/2000 -0500, Alan K. Adamson wrote:
>Doesn't it have to do with the fact that Rubber balloons are porous and you
>not only let some of the helium out, but you also converted some to another
>gas.  Osmosis at it's best.
>
>Mylar won't do that, well, no at much that is.
>
>Course, you probably didn't tell us you had to taste a little along the way
>:-).
>Alan
>
>-----Original Message-----
>From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
>Behalf Of Bob Bruninga
>Sent: Friday, March 10, 2000 2:53 PM
>To: TAPR APRS Special Interest Group
>Cc: amsat-bb@AMSAT.Org
>Subject: [amsat-bb] Whats in Helium?
>
>
>While prototyping our next APRS MIM high-altitude telemetry Balloon, I
>filled up a party balloon to 18" with helium from the balloon store.
>
>One  Day later it had lost ALL its lift (as expected), but it was still
>2/3rds inflated.
>
>What is this 2/3rds if it aint helium?  Did I get sold some bad gas?
>Or does party gas not contain mostly Helium?
>
>THis is not just a one time observation.  Kids balloons all seem to
>shrivel to about 1/2 volume once all the Helium has permeated out of the
>balloon.  What's still in there and did I pay for it?
>
>WB4APR
>
>
>
>----
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>----
>Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
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>


"When the freedom we seek is the freedom from responsibility, we cease to
be free." 

**************************************
Jamie Hutches
Harding University, Searcy, Arkansas
501-279-5823
jmhutches@harding.edu
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