# Thread: Perpetual Energy- the expansion of freezing water

1. Today I had a thought. If water expands when it freezes, what would happen if you were to fill an unbreakable box 100% with water and freeze it. Meaning The water, by nature, must expand but cannot because of limited space. what would happen?
A few questions and Ideas brought up by a few people I asked this question:
1. Would the water simply not freeze?
2. Is there such a material that would not be broken by the expanding water?
3. Would the water, in attempting to expand and being unable to, create heat, stop expanding (and cool down), and then repeat the process?

I know very little of the properties of water, or why it expands, so maybe this is just a ridiculous thought.

The idea is that this box would be in a place where energy is not required to generate low temperatures (e.g space?)

Thank you!

2.

3. As long as you kept the temp low enough to freeze the water you will end up with compressed ice. The density of ice is less than water at the same temp and pressure. 0° water will be more dense than 0° ice at standard pressure. If you continue to cool ice further, it will contract, and ice at higher pressure can be less dense than water. So what you end up with is ice pushing against the interior walls of the container.

4. Originally Posted by Janus
.... ice at higher pressure can be less dense than water.
By saying it can be less dense instead of saying it will be less dense do you mean that it could however become more dense?

5. I would agree with Janus - you will most likely end up with a box full of ice under high pressure. Nothing else could really happen, because the water will freeze given a low enough temperature, and the ice has nowhere to go.
Btw, you would need one hell of a solid box :-D

6. There are different forms of ice. I'm not sure which one you would end up with, some forms have a density greater than water.
Ice - Wikipedia, the free encyclopedia

Ice III A tetragonal crystalline ice, formed by cooling water down to 250 K at 300 MPa. Least dense of the high-pressure phases. Denser than water.
Ice XII A tetragonal, metastable, dense crystalline phase. It is observed in the phase space of ice V and ice VI. It can be prepared by heating high-density amorphous ice from 77 K to about 183 K at 810 MPa. It has a density of 1.3 g cm−3 at 127 K (i.e., approximately 1.3 times more dense than water).

7. If you design your very, very, very strong box correctly, you might just possibly end up with super-cooled water. But the pressures involved would be ginormous.

(You could cheat and add some salts to mimic how this happens with maximum pressure at the bottom of very deep ice-covered ocean waters, but then it'd be brine.)

8. Ice is lighter than liquid water because the ice crystal is an open hexagonal structure with space in the middle. This is the prefered shape for solid forms of H2O. It forms this shape due to the angle between the two hydrogen atoms of the H2O molecule. If you force h2o into a solid state but don't allow it to form its preffered molecular shape it will find its next most preffered molecular shape. It is possible that this second form might even be stable. Carbon can from 3 types of stable soilid molecules with radically different physical properties; graphite, diamond, and buckminsterfullerine.

9. That was a great answer, thank you

10. But be very careful with Ice 9. A global catastrophe involving freezing the Earth's oceans by simple contact with ice-nine would spell doom for all of us...

Cat's Cradle - Wikipedia, the free encyclopedia

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