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Re: PHYS-L Digest - 30 Nov 2001 to 1 Dec 2001 (#2001-473)



At 21:36 -0600 12/1/01, E.C. Muehleisen wrote:

The density of water increases to a maximeum at about 4 degrees Celsius. As
the temperature continues to decrease, the density decreases. Hence ice
floats in water. However, if one believes the volume versus teperature curve
as shown in Hewitt, then one must believe that the density of hot (above 20
degrees celsius) is less than that of ice. Why, then, does ice float in very
hot, nearly boiling, water?

Assuming that Hewitt got his data right, I would guess that if the
ice you are talking about is what comes from your refrigerator, or
most ordinary sources, it comes with lots and lots of bubbles trapped
in it, which effectively lowers its density, and so it is still able
to float in very hot water. To get ice that behaves properly, you
probably will have to start with distilled water that has no
dissolved gases in it. Check with your chemistry dept. They probably
can come up with some of that kind of water.

Hugh
--

Hugh Haskell
<mailto://haskell@ncssm.edu>
<mailto://hhaskell@mindspring.com>

(919) 467-7610

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