kind of random water/ice properties questions

[im a model]

does regular ice, gradually frozen from water, under normal pressure, ever get to a density greater than water? i saw that at like -180 C it still wasnt even close, but wouldnt it have to be at -273 C (absolute zerosville)?

on a related note, what is the coldest temperature humans can produce?

also, my understanding of temperature was that stuff is warm because of particles flying around and hitting it and giving it energy, so why isnt a vaccuum (no particles, like space) 0 Kelvin?

moreover, it seems like a lot of the fancy ices like phase II, III, IV, etc. are made under high pressure and these are denser than water. so essentially high pressure (like hundreds of mega pascals) will make the ice freeze in denser crystals, and then even when you remove the pressure, it will still be high-density and will sink in water?

and does pressure make the freezing/melting point lower? like if i have a block of ice in a room and the room is like 2 degrees celsius, could i save my block of ice by increasing the pressure to several hundred mega pascals? or would the ice melt and refreeze into a phase II or III or whatever with a denser structure?

lastly, can water be frozen into a glass by freezing it really quickly, like metals and other materials can be, that would be denser than water? (are glasses generally denser than the material would be naturally at the same temperature?)

thanks for any responses and i apologize if any of the questions are too retarded to allow for a worthwhile respose.

[Arp220]

I'm pretty sure that ice under 'normal' pressure never achieves a density greater than that of water, no matter how cold you get, but I could be wrong about this, Something ultraweird might happen as you get near 0K.

Coldest temperature humans have produced is a few millionths of a degree above 0K

An absolute vacuum has nothing in it, so it has nothing in it to 'have' any temperature. So its not at 0K, because that staement presupposes that theres something in there that has the property of temperature.

I have no clue what happens to high density ice that is placed in 'normal' pressure.

ok sorry have to work now, will try to do the rest later...

[daryn]

space is freezing dude. the avg temp of the universe is something like 4 K

[m_the0ry]

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does regular ice, gradually frozen from water, under normal pressure, ever get to a density greater than water? i saw that at like -180 C it still wasnt even close, but wouldnt it have to be at -273 C (absolute zerosville)?

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Once in the form of a solid the molecules form a lattice. That is, they form some periodic structure if it is physically possible. The lattice that water forms has big holes in it. It doesn't matter how cold ice is, it still has the same kind of lattice, and it will still be in a lattice with big holes and thus lower density than liquid. Note that this assumes standard pressure. Additional pressure can change the equilibrium state of the atoms in a lattice. It would be pure speculation for me to say whether or not ice becomes more dense at a certain pressure than liquid at the same pressure. For that we'd need some sort of triple point volume graph, which is a lot of measurements. I'm sure it's out there somewhere but I don't want to look for it.

[ QUOTE ]
on a related note, what is the coldest temperature humans can produce?

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We have cooled hundreds/thousands of atoms to nanokelvins. That is, ~.000000001 degrees celcius (or kelvin, same thing) above absolute zero. It is physically impossible to make matter reach absolute zero, but one can get very close. Macroscopic objects on the other hand are much harder to cool this much because the cooling technique involves lasers, which can only affect surface area. An atom is all surface area (simplified) but a large object has a lot of volume that isn't touched by the laser. As far as I know there have only been a few large objects brought close to absolute zero. The standard lower bound on freezing a large object is immersion in liquid helium which gets it to about 2.5 Kelvin (2.5 celsius above absolute zero).

[ QUOTE ]
also, my understanding of temperature was that stuff is warm because of particles flying around and hitting it and giving it energy, so why isnt a vaccuum (no particles, like space) 0 Kelvin?

[/ QUOTE ]

Temperature is a very complicated construct we have to describe matter. Trying to assess the temperature of a true vacuum is like trying to assess the color of vacuum. For example, classically temperature is considered to be the average kinetic energy of a particle in a system (QM-wise, it's a bit more complicated), or the sum of kinetic energies divided by the number of particles. Obviously when we have zero particles, we have a divide-by-zero error and our definition of temperature sort of falls apart.

There are more definitions of temperature now, thanks to QM and thermodynamics, and in reality radiation and vacuum perturbation gives vacuum a certain amount of energy, and arguably thus a temperature. But as far as we and our baryonic-matter-centric lives are concerned, the temperature of vacuum is sort of asking the wrong question.


The rest of your answers are best explained by looking into the Triple Point

[GoRedBirds]

Google water phase diagram. If you image search you can find some really detailed ones that show extreme pressures and multiple triple points. Here's a good example.