[neilep (OP)]

Under Pressure....great tune by Queen and David Bowie but can water be under so much pressure that it can effectively become more viscous or solid ?...I know that in the deepest ocean the pressure is 16,000 pounds per square inch but there never seems to be an indication that the water itself is squashed !!!

Release that tension and let the answer be all runny and gooey.

 Many Thanks


<font color="blue">'Men are the same as women...just inside out !'</font id="blue">

[DrN]

Hi, water is pretty special, it is actually less dense as a solid than it is at 4 C - liquid! something to do with the rigid bonds that make the solid pushing the H2O molecules further apart than when they were just a pretty cool liquid. as it heats up above 4 C i think it becomes less dense again, probably something to do with the extra energy causing the molecules to buzz around. I can't really remember it all exactly!

If i remember rightly this amazing property of water is due to its dipole, the charges on the hydrogens and oxygen are unevenly distributed, so electrostatic interactions form - hydrogen bonds.

to be honest, I've got no idea if water can be condensed under pressure. because I've what I've said above i would guess it would have to remain a liquid in any case.

i hope someone can enlighten you a little more than I'm able to!

[qpan]

Water is less dense in solid form due to hydrogen bonding - without this special type of bonding, life would probably not exist as instead of ice forming on the surface of water and creating an insulating layer, it would sink to the bottom causing far quicker freezing of all the water.

Water is very difficult to compress, like all liquids. In very deep areas of sea (1-2 miles deep) the water pressure compresses the height of the sea by only several metres (5-10 metres)!

"I have great faith in fools; self-confidence my friends call it."
-Edgar Allan Poe

[OmnipotentOne]

I know this really isnt an answer, but I remember watching cartoons and such where they dived so deep in the sea that eventually they crashed through a ceiling of water and ended up in a cave.  They would get out of there sub, look around to see water flowing upward into the semi solid wall of h2o above.


I wonder if its possible....[?]

To see a world in a grain of sand.

[Broca]

http://www.nature.com/news/2004/040920/full/040920-2.html

[neilep (OP)]

Thanks for the link Broca......that's about as gooey as you can get !..thanks

'Men are the same as women...just inside out !'

[Broca]

Your welcome Neil...I tossed it on without much fanfare this afternoon...but when I saw it, sad to say, I thought of you! :-) I found the results of that study most amazing, not what you would have thought.

[Monox D. I-Fly]

http://www.nature.com/news/2004/040920/full/040920-2.html

"The best swimmer should have the body of a snake and the arms of a gorilla," recommends Cussler.

So that's why gators are excellent swimmers.

[Petrochemicals]

Water is a strange substance, very light comparitavley but a huge thermal capacity, and as has been stated large in volume r in its hexagonao form ice than as liquid. Has a triple point of zero, and exists as a vapour and a solid beneath freezing in standard pressure of earth.

Liquid water on earth becomes more d3nse toward about 4 degrees and then becomes less dense as you approach 100c.

Super cooling water under standard pressure leads to water below freezing by some way, and this leads to glasy ice, with no cristaline s5ructure, only amphimorous glass like structure. Super cooled water is slightly d3nser than standard 1g cc.

Pressurizing water and heating it can lead to high temperature ice that is solid at room temperature and atmospheric pressure , and the only way to return it to normal phaze h20 is to heat it further.

Water compresses slightly so i would say that greatest density is probably under huge pressure at 4 degrees. Although this pressure will undoubtably move the scales so illl take a guess at about 30 dcentigrade at a black smoker.

[Kryptid]

With sufficient pressure, you could probably turn water into degenerate matter (like that which exists inside of white dwarf stars). That would be a density of 10⁴ - 10⁷ g/cc. This assumes that you keep the temperature low enough in the process to keep the hydrogen in the water from fusing, of course.

[wolfekeeper]

You're asking multiple questions here, including whether it can be solid under pressure. I don't think the density of water changes that much with pressure, but ice exists in very many different forms. I think about the densest is Ice XII which is 1.3 times the density of water:

https://en.wikipedia.org/wiki/Ice_XII

It forms at pressures of 5400 atmospheres at -13C. However, it's only metastable. I'm not sure whether you can have it at normal pressures, if so you could drop it into water and it would readily sink!

The phase diagram for water/ice is complicated:



(note that ice XII isn't on this diagram, apparently because it's metastable.)

More at ice:

https://en.wikipedia.org/wiki/Ice

[Bored chemist]

You're asking multiple questions here,

They were asking multiple questions- a dozen years or so ago.

[wolfekeeper]

And still nobody had really answered it!

[chris]

You're asking multiple questions here,

They were asking multiple questions- a dozen years or so ago.

It's terrific that we're revisiting some of these ancient gems, which date from the very early days of the Naked Scientists - amazing really that many of us are still here and still doing this!

Right, shall we try and answer it!?

[alancalverd]

I think Wolfekeeper's phase diagram answers the question regarding solidification at high temperatures. Under ambient conditions the liquid compresses at about 0.5% per atmosphere additional pressure, so the density of "normal" water can indeed vary a bit, and at 1000 atm or at the bottom of the sea it will indeed be substantially denser than the stuff in your tap.

[chris]

I think Wolfekeeper's phase diagram answers the question regarding solidification at high temperatures. Under ambient conditions the liquid compresses at about 0.5% per atmosphere additional pressure, so the density of "normal" water can indeed vary a bit, and at 1000 atm or at the bottom of the sea it will indeed be substantially denser than the stuff in your tap.

Alan - when we say in physics lessons that liquids are incompressible, is that a small lie? For water to become denser at greater depth, as we know it does and as you have mentioned above, then it must be compressing a bit. So are physics teachers lying when they say this?!

[wolfekeeper]

Well, they usually say it's almost incompressible. The compressibility of water is about 1% at 200 atmospheres (compressibility varies, but is about 4.4 to 5.1 x 10^-10/Pa). So for example, the pressure at 11km depth at the bottom of the Mariana Trench is about 1000 atmosphere, so the water will be compressed about 5%.

Actually if you look at the diagram, if you just increase the pressure from normal liquid water, along most of the curve you find you form Ice VI, which, while not metastable, is also interesting:

http://www1.lsbu.ac.uk/water/ice_vi.html

If you read the page, it too has a slightly higher density than water, even the high pressure water around it which has been compressed, so it too would sink.

Unfortunately that would take several times the pressure to form than you find at the bottom of the Mariana Trench, so humans will never see a snowy bottom in our Bathyspheres.

[alancalverd]

Alan - when we say in physics lessons that liquids are incompressible, is that a small lie? For water to become denser at greater depth, as we know it does and as you have mentioned above, then it must be compressing a bit. So are physics teachers lying when they say this?!

It's only a bit more of a lie than Newtonian physics - the approximation is good enough for everyday use. But if a substance were truly incompressible, the speed of sound would be infinite as every molecule would have to move at the same time.

[chris]

if a substance were truly incompressible, the speed of sound would be infinite as every molecule would have to move at the same time.

Thank you for that excellent point - I'd not made that obvious connection in my own mind.

[alancalverd]

Unfortunately

No, it's very fortunate! If the oceans froze from the bottom upwards,the climate would be very different and life would probably not have evolved.

Almost every terrestrial phenomenon that is ascribed to God is actually caused by the hydrogen bond.