The water that wouldn't freeze...

[Zebo]

Originally posted by: Skoorb

Originally posted by: Zebo
The water is frozen, called amorphous ice. The only thing stopping from crystalline ICE as you know it is pressure represented by this phase diagram.

http://www.lsbu.ac.uk/water/phase.html

Ah, the memories, they hurts us.

There was a site on the net and the guy did the superheating thing and filmed it a few times. He'd use a microwave and a cup and when a fork was inserted the water blew up. It's easier in a microwave to superheat water than on a stove AFAIK.

That's because the microwave keeps spinning and stretching the hydrogen molecules (what causes the heating) long after you take it out heating the water or matrix he used to even higher temps. very dangerous.

 

[WinkOsmosis]

Super cooling? Super heating? When did we all become pseudoscientists? There's no super anything. It's called ICE BEING LESS DENSE THAN LIQUID WATER. Water needs room to expand in order for ice crystals to form. If there's no room to expand, it stays liquid.

Originally posted by: DurocShark
Zebo nailed it. Pressure lowers the freezing point of water. The higher the pressure, the lower the freezing point. And the higher the boiling point too...

The discussion about boiling water...

Here's an experiment for ya'll. It's dangerous so make sure you're protected.

Get a ceramic bowl. One with no scratches or cracks in it. Fill it 3/4 full with water. Put it in your microwave with the carousel removed and cook on high for 2 minutes. Don't disturb it... Let it cool completely. Cook it again for 4 minutes.

Now, you should notice that the water still isn't boiling. Wearing your fireproof underoos and a face shield and some waterproof gloves, toss a toothpick or something in the bowl of water.

Scalding water explosion!

That has nothing to do with pressure. The water just needs a surface for bubbles to form on.

 

[Zebo]

Originally posted by: WinkOsmosis
Super cooling? Super heating? When did we all become pseudoscientists? There's no super anything. It's called ICE BEING LESS DENSE THAN LIQUID WATER. Water needs room to expand in order for ice crystals to form. If there's no room to expand, it stays liquid.

Originally posted by: DurocShark
Zebo nailed it. Pressure lowers the freezing point of water. The higher the pressure, the lower the freezing point. And the higher the boiling point too...

The discussion about boiling water...

Here's an experiment for ya'll. It's dangerous so make sure you're protected.

Get a ceramic bowl. One with no scratches or cracks in it. Fill it 3/4 full with water. Put it in your microwave with the carousel removed and cook on high for 2 minutes. Don't disturb it... Let it cool completely. Cook it again for 4 minutes.

Now, you should notice that the water still isn't boiling. Wearing your fireproof underoos and a face shield and some waterproof gloves, toss a toothpick or something in the bowl of water.

Scalding water explosion!

That has nothing to do with pressure. The water just needs a surface for bubbles to form on.

Bubbles WTF?

What do you think "room to expand" is? In the science world this is known as pressure. I'm sorry you can't read the phase diagram which clearly shows the freezing point and want to call people names but here maybe is a more qualitative explination for you I'm done.

11 Pressure reduces its melting point (13.35 MPa gives a melting point of -1°C)
Increasing pressure normally promotes liquid freezing, shifting the melting point to higher temperatures. This is shown by the forward sloping liquid/solid line in the phase diagram. In water, this line is backward sloping. As the pressure increases, the water equilibrium shifts towards a collapsed structure (e.g. CS ) with higher entropy. This lowers the melting free energy change (DG=DH-TDS) such that it will be zero (i.e. at the melting point) at a lower temperature. The minimum temperature that liquid water can exist without ever freezing is -21.985°C at 209.9 MPa; at higher pressures water freezes to ice-three, ice-five, ice-six or ice-seven at increasing temperatures. Stretching ice has the reverse effect; ice melting at +6.5°C at about -95 MPa negative pressure within stretched microscopic aqueous pockets in mineral fluorite [243].

It should be noted that ice skating does not produce sufficient pressure to lower the melting point significantly; the slipperiness being generated by frictional heating. [Back]

From same site.

 

[tkdkid]

IIRC the thread in question involved a soda bottle. The soda didn't freeze because it is under pressure. As pressure increases, the temp required to freeze becomes lower. When the bottle was opened, the pressure was released, and so the soda then froze.

Soda is pressurized so that the carbon dioxide can be dissolved in the liquid. When the pressure is released by opening the bottle or can, the carbon dioxide is slowly released from the solution.

 

[Trevelyan]

Well using bottles isn't always gonna work, since most of the time the thin bottle won't be able to stop the building pressure inside it, and it will just explode.