Thanks decimon.
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Posted on 11/23/2011 8:15:10 PM PST by decimon
Utah chemists: Water doesn't have to freeze until minus 55 Fahrenheit
SALT LAKE CITY -- We drink water, bathe in it and we are made mostly of water, yet the common substance poses major mysteries. Now, University of Utah chemists may have solved one enigma by showing how cold water can get before it absolutely must freeze: 55 degrees below zero Fahrenheit.
That's 87 degrees Fahrenheit colder than what most people consider the freezing point of water, namely, 32 F.
Supercooled liquid water must become ice at minus 55 F not just because of the extreme cold, but because the molecular structure of water changes physically to form tetrahedron shapes, with each water molecule loosely bonded to four others, according to the new study by chemists Valeria Molinero and Emily Moore.
The findings suggest this structural change from liquid to "intermediate ice" explains the mystery of "what determines the temperature at which water is going to freeze," says Molinero, an assistant professor at the University of Utah and senior author of the study, published in the Thursday, Nov. 24 issue of the journal Nature.
"This intermediate ice has a structure between the full structure of ice and the structure of the liquid," she adds. "We're solving a very old puzzle of what is going on in deeply supercooled water."
(Excerpt) Read more at eurekalert.org ...
Cold as ice ping.
Hot water freezes faster than cold water.
cryogenics?
the mystery of "what determines the temperature at which water is going to freeze
Sometimes I am amazed by what we don't know rather than what we do know.
We don't know when water will freeze, we understand very little about gravity, we haven't a clue about the composition of space, and no one knows what Newt is going to say next.
"In physics, cryogenics is the study of the production of very low temperature (below −150 °C, −238 °F or 123 K)..."
http://en.wikipedia.org/wiki/Cryogenics
Sometimes. The Mpemba Effect.
University of Utah - they have salt in their water there, so this result is not surprising.
I noticed the other morning that clear distilled water in a motorcycle radiator with no antifreeze was not frozen with the air temp at 20F and the radiator metal temp at 26. Have seen this many times before and so am not worried about freezing (at least damaging hard freezing) in this temperature range. Has been replaced with non-aqueous propylene glycol now.
We're doomed.
On sunny days, I have seen water running in the streets from snow melt at -26 F.
If ice were heavier than water, lakes and rivers would freeze from the bottom up, and they would freeze solid. Very few fish would be able to survive that. As it is, ice provides a layer of insulation on top of bodies of water, so that the bulk remains liquid, except in shallow bodies of water and regions near the polar caps.
Water is a very strange chemical. Without its weird properties, life would be impossible.
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