It Takes 275 Water Molecules To Make Ice

http://www.scientificamerican.com/podcast/episode.cfm?id=it-takes-275-water-molecules-to-mak-12-09-26

by co_pl_te • 14 years ago

67 13 14 years ago

scientificamerican.com

xsace• 14 years ago

So where is the picture?

RollAHardSix• 14 years ago

Picture as in general understanding, not as in photo. I believe.

jonsen• 14 years ago

Link in comment:

http://physicsworld.com/cws/article/news/2012/sep/21/how-man...

Jabbles• 14 years ago

Irritating headline (and summary) makes it sound like some kind of hard number at which ice (starts) to form. The abstract states "Spectral features indicating the onset of crystallization are first observed for n = 275 ± 25"

koide• 14 years ago

The uncertainty coming from the spectral analyzer and not from the water itself, I expect.

Retric• 14 years ago

It's probably both. What there looking for is an optical change which only indirectly relates to if something is 'ice' or not. And I suspect depending on which part's of the lattice are missing and where the light source is would change the optical property's.

stephengillie2• 14 years ago

So a body of water won't turn into ice if the body of water has only 274 molecules?

Can we make a kind of "ice-steam" of below-freezing water molecules suspended in air or another medium?

JoeAltmaier• 14 years ago

Can do that anyway, with any amount of water: put it in a vacuum. It vaporizes and freezes at the same time.

stephengillie2• 14 years ago

True, but water can still clump in a vacuum

bkanber• 14 years ago

The subtitle of this article irks me:

> the change to ice occurs at 275 H20s.

That's a zero, not the letter O, in "H20s".

blerrrgh• 14 years ago

A general had a problem: mud. Marines have slogged their way through it for generations. Is it possible to get rid of mud? Without having to carry anything heavy? Marines already have enough to carry.

Dr. Felix Hoenikker, an original thinker, found the "outside-the-box" answer; a single crystal of Ice-Nine would crystallize every bit of water it touched.

"...suppose, young man, that one Marine had with him a tiny capsule containing a seed of ice-nine, a new way for the atoms of water to stack and lock, to freeze. If that Marine threw that seed into the nearest puddle...?"

"The puddle would freeze?" I guessed.

"And all the muck around the puddle?"

"It would freeze?"

"And all the puddles in the frozen muck?"

"They would freeze?"

"And the pools and the streams in the frozen muck?"

"They would freeze?"

"You bet they would !" He cried. "And the United States Marines would rise from the swamp and march on!"

terhechte• 14 years ago

I had to think about the same book when I read the title (Cat's Craddle, Vonnegut)

andrewcooke• 14 years ago

this is explained a lot better at http://www.mpg.de/6362003/water-ice-crystal :

In ice crystals, the water molecules arrange themselves in a six-sided, or hexagonal, to use the scientific term, spatial lattice. Each water molecule forms chemical bonds, so-called hydrogen bonds, to four adjacent molecules. This honeycomb crystal lattice of water ice requires more space than liquid water, which is unusual. As long as the water clusters have not reached the minimum size for a crystal, the Göttingen experiment presents them with a dilemma. The experiments take place at around minus 180 to minus 150 degrees Celsius - the molecules are therefore much too cold for a liquid. For a crystal, however, they are still too few in number. The tiny clusters escape this quandary by forming a type of liquid that has clotted in the cold: they form a rather disordered, “amorphous” spatial lattice.

If the cluster now grows, the water molecules at its core can change at some stage from the disordered chemical game into the crystalline structure by each of them taking four neighbours by the chemical hand. 275 water molecules thus create the initial beginnings of a real ice crystal with hexagonal structure in the interior of the cluster. To begin with, this structure is still slightly deformed; however, as the cluster grows in size, this interior grows to become a nicely ordered ice crystal, while the outer layers remain amorphous. “When there are 475 molecules, the very core is already perfect,” says Buck.

also, http://physicsworld.com/cws/article/news/2012/sep/21/how-man...

It Takes 275 Water Molecules To Make Ice

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