Scientists Freeze Water with Heat

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Imagine water freezing solid even as it's heating up. Such are the bizarre tricks scientists now find water is capable of.

Popular belief contends that water freezes at 32 degrees Fahrenheit (0 degrees Celsius). Surprisingly, if water lies in a smooth bottle and is free of any dust, it can stay liquid down to minus 40 degrees F (minus 40 degrees C) in what's called "supercooled" form. The dust and rough surfaces that water is normally found in contact with in nature can serve as the kernels around which ice crystals form.

Now researcher Igor Lubomirsky at the Weizmann Institute of Science in Rehovot, Israel, and his colleagues have discovered another way to control the freezing point of water — via what are called quasi-amorphous pyroelectric thin films. These surfaces change their electrical charge depending on their temperature.

When pyroelectic surfaces are positively charged, water becomes easier to freeze, and when they have a negative charge, it becomes harder to freeze.

The researchers saw that supercooled water could freeze as it's being heated, as long as the temperature changes the surface charge as well. For instance, when supercooled water is on a negatively charged lithium tantalate surface, it will freeze solid immediately when the surface is heated to 17.6 degrees F (minus 8 degrees C) and its charge switches to positive.

Curiously, positively charged surfaces inspire supercooled water to freeze from the bottom up, while negatively charged surfaces cause it to freeze from the top down. This likely has to do with how water molecules orient themselves — the negatively charged oxygen atoms in water molecules naturally point toward positively charged surfaces, while the reverse is true with hydrogen atoms.

"The difference between the positive and negative charge was unexpected," Lubomirsky said.

The ability to better control the freezing temperature of supercooled water could be critical for a variety of applications, including the survival of cold-blooded animals, the cryo-preservation of cells and tissues, the protection of crops from freezing, and the ability to understand and trigger cloud formation.
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http://www.livescience.com/strangenews/water-freeze-heat-100211.html

Love how we are learning to think differently about things :)
 
I don't exactly understand what's happening here....can any of you geniuses put it into laymens for me?
 
Keeper said:
I don't exactly understand what's happening here....can any of you geniuses put it into laymens for me?
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Yes, normally water freezes around 0 degrees Celsius.

However, if the water is free from impurities, you can "supercool" that water to lower than 0 degrees.

They also found that when they play around with stuff, they can make water freeze (form ice) from the top of the water, or from the bottom upwards.
 
Keeper said:
I don't exactly understand what's happening here....can any of you geniuses put it into laymens for me?
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The are "polarizing" the water.

When pyroelectic surfaces are positively charged, water becomes easier to freeze, and when they have a negative charge, it becomes harder to freeze.
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Thus when the water is "negatively charged" it is harder to freeze.
 
Keeper said:
I don't exactly understand what's happening here....can any of you geniuses put it into laymens for me?
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1. Superfreze pure water but don't give the water any imputities, then it remains liquid.
2. Now add an electric charge to polarise the superfreezed still liquid water.
3. Now heat the superfreezed still liquid water up a bit and at about -8 degree's C, it will freeze.

Depending on the polarising direction, the water will freeze (form crystals) from the bottom or the top.
 
With nano tech this can lead to supercooling in a different way.

Think layers of super cooler water (singular mol.) between single layer mol of superconductors.
 
hmm.... but can't you freeze supercooled water just by touching / poking / shaking it?

IIRC you can supercool beer as well.
 
Would of been cool if they managed to freeze it at above 0 degrees C.
if water lies in a smooth bottle and is free of any dust, it can stay liquid down to minus 40 degrees F (minus 40 degrees C)
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That cant be right...
 
Keeper said:
hmm.... but can't you freeze supercooled water just by touching / poking / shaking it?

IIRC you can supercool beer as well.
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It does because by shaking you ad energy to the "mix" and thus by causeing "rippels" you make it easier for the crystal structure to form.

Park@82 said:
Would of been cool if they managed to freeze it at above 0 degrees C. That cant be right...
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Ah as pointed out -40F = -40C....
 
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