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Author Topic: What happens to water if you compress it more and more and more...  (Read 33817 times)

Offline Seany

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Ahh.. That is so interesting Ben.. But personally, I don't think a black hole can be made by adding lots of pressure.

I thought that blackholes were made, when stars run out of gases to burn and eventually shrinks so small, but with a mass so big, turning into a black hole. Well, that's what I thought.
 

Offline DrDick

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I have tried to make a crude phase diagram for water using the diagram creation ability of the board.  I haven't tried this before - let's see how it works.   :-\

Compression of water has different effects depending on the conditions at the time.  Compression does release heat, but if you do it slowly enough, the heat is lost during the compression.

Looking at the phase diagram, there is a region where if you increase the pressure at constant temperature, solid water (ice) will change into liquid water (melting).  For quite some time, it was thought that this was how skating worked, by melting a thin layer of ice below the skates.  Now it is realized that any melting from this effect would be too slow to have any effect, and there are other (more complex) reasons given.

If you keep increasing the pressure, however, the liquid will eventually solidify again - not from getting colder, but from increased pressure.  Of course, this would be a different kind of ice than what we're used to.  There are several different phases of solid water, with phase boundaries between them just as there are phase boundaries between solid and liquid phases, or liquid and gas phases, etc.

Eventually, with enough pressure, the molecules of water would get close enough that the hydrogen atoms would start combining and you would get nuclear fusion.

Keep going, and you would eventually get the black hole mentioned earlier.

Dick
 

Offline Seany

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Oh. Thanks DrDick. It makes sense now. Quite scary, the whole thing :o
 

Offline DrDick

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Oops, I forgot to insert the drawing into the message. [:I] Let's try again.   (Should've previewed the message first, I guess.)




 

Offline Seany

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Lol I was wondering what you were going on about the diagram lol :D
 

paul.fr

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the first thing that happens when pressure is applied to a molecular system such as water is that the distance between the molecules is reduced and if there are any rotations or phase changes etc. that can happen to reduce the stress [LeChatelierís principle] they will happen. This is what happens in the water-normal ice [Ice Ih or hexagonal ice]. This ice is less dense that water so if a pressure is applied to a system of this ice and water the ice simply melts [or possibly vaporizes if the pressure is from an inert gas] to reduce the pressure and the freezing point lowers.

http://www.madsci.org/posts/archives/mar97/859148048.Ph.r.html ice is described here" http://skua.caltech.edu/hermann/ice.htm

The next link describes it all with a good phase diagram. http://www.ill.fr/AR-97/page/05chemi.htm

It is rather difficult to compress the space between atoms in a simple molecule because there is no space; there are electrons in their lowest orbitals. These orbitals usually occupy the smallest possible volume and while they are compressible the energy required is fantastically high and there are no readily available relaxation processes that allow a lower volume. One possible mechanism is positive ion formation with ejection of an electron [piezoelectric effect] since positive ions are usually much smaller than the neutral atom or molecule. Topics to look up here are Vibrational and electronic spectra of molecules and the Franck-Condon Principle. These show that pressure, while raising the energy of a molecule, doesnít usually permit excitation of that molecule to higher energy states because the higher states are of greater volume. So what can happen?

Molecules can rearrange to forms that are of less volume; the classic example is the graphite to diamond transformation. Crystal forms can rearrange to more compact forms. Finally in water there are weak bonds, hydrogen bonds, that have longer than normal bond lengths. These are compressible. All these things happen in ice at extremely high pressures. It also happens that some of these ice forms are stable at temperatures above zero C to really quite high temp possibly even to the critical point. The second and third links describe the processes well. The third link has a good phase diagram describing the many phases of ice and several models of some of the structures.  however, the compression still is not really taking place in the atom but in the longer bonds between molecules. However, at least one form might contain hydronium[H3O+]] ions which means that the space between the H and O atoms was compressed to force a rearrangement.

« Last Edit: 13/04/2007 18:08:57 by paul.fr »
 

Offline Seany

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Sorry Paul! I know you're trying to help, but as a 13 year-old.. I really can't understand. I've read it through twice :o
 

Offline Batroost

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Or if you want to see it from a slightly different point of view... Ice comes in different kinds which depend on both pressure and temperature.

Try typing Ice I, Ice II, Ice III, Ice IV, Ice V, Ice VI etc... into Google.

Ice I is the 'normal' Ice you find in a fridge. The others form under different pressures and temperatures.

Ice VI looks particularly interesting:- forms from Water at ~273 K (that's its normal 'freezing point') and 1.1 GPa pressure (that's about 10,000 atmospheres)! Appears to be stable at higher temperatures (>80 degrees C) if you increase the pressure and has a higher density than water.

So... depending on how you vary the temperature and pressure there are a range of different Ices you could end-up with.
 

Offline Ben6789

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But what about the black hole? After it's created what will happen to the equipment compressing it? Warped? Destroyed? Sucked to another dimension?
 

Offline Seany

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Ben, I guess we will never find out :(
 

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