Date: Mon, 16 Aug 2010 09:04:44

Author: Cliff Bettis

Subject: Poly Density Bottle

Post:

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I just got a Poly Density Bottle from Educational Innovations
(http://www.teachersource.com/Density/Density/PolyDensityKit.aspx). It
contains two different colored groups of beads (purple and white) of
different densities, and you fill the bottle halfway with salt solution and
the other half with isopropanol. Well, when I got the kit, I figured I ought
to do it carefully, so I walked across campus to visit my pals in the
chemistry department to score some DI water and some isopropanol. All they
had was 99% isopropanol so we had to dilute it a bit, but after mixing up
our solutions we were successful in getting it working. As I walked back to
the physics building, about a 5 minute walk, I noticed the white beads in
the bottle were turning violet. I was thinking maybe I shouldn't have
trusted chem.. dept. isopropanol, that maybe some how it was leaching color
out of the purlpe beads and dyeing the white ones. I got back to the physics
building and as I walked down the hallway, I noticed my violet beads had
turned back to white! Apparently the manufacturer uses the same beads that
they sell as UV detecting beads which change color when exposed to UV. When
I was outside walking, they were in the sunshine.



Cliff


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I just got a Poly Density Bottle from Educational =
Innovations
(http://www.teachersource.com/Density/Density/PolyDensityKit.aspx).
It contains two different colored groups of beads (purple and white) of =
different
densities, and you fill the bottle halfway with salt solution and the =
other
half with isopropanol. Well, when I got the kit, I figured I ought to do =
it
carefully, so I walked across campus to visit my pals in the chemistry
department to score some DI water and some isopropanol. All they had was =
99%
isopropanol so we had to dilute it a bit, but after mixing up our =
solutions we
were successful in getting it working. As I walked back to the physics
building, about a 5 minute walk, I noticed the white beads in the bottle =
were
turning violet. I was thinking maybe I shouldn’t have trusted =
chem..
dept. isopropanol, that maybe some how it was leaching color out of the =
purlpe
beads and dyeing the white ones. I got back to the physics building and =
as I
walked down the hallway, I noticed my violet beads had turned back to =
white!
Apparently the manufacturer uses the same beads that they sell as UV =
detecting
beads which change color when exposed to UV. When I was outside walking, =
they
were in the sunshine.



Cliff







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