Say you fill a strong water proof safe with water then take it to well below freezing – does the water stay liquid as long as the safe doesn't break?

Is it on a conveyor belt?

Yes, if it truly can't expand it'll remain liquid. But don't underestimate the forces created by the water, they're huge. You'd need one hell of a safe to withstand it.

it possibly wouldn't be an issue unless you removed all the trapped gases from the water first and completely filled the safe. Otherwise it wouldn't cause a problem. Are safe doors watertight too?

is it expensive water?

Does a variation on Boyle's law apply?

So with a hypothetically unbreakable container completely filled with pure water, devoid of dissolved gases, etc. and taken to below freezing, the water would remain liquid, right…?

Wow.

If the increase in volume on freezing is prevented, an increased pressure of up to 25 MPa may be generated in water pipes; easily capable of bursting them in Winterb. An interesting question concerns what would happen to water cooled below 0°C within a vessel that cannot change its volume (isochoric cooling). Clearly if ice forms, its increased volume causes an increase in pressure which would lower the freezing point at least until the lowest melting point (-21.985°C) is reached at 209.9 MPa.e A recent thermodynamic analysis concludes that ice nucleation cannot arise above -109°C during isochoric cooling [1053], which is close to the upper bound of the realm of deeply supercooled water (-113°C), so it is unclear if ice would ever freeze in such a (unreal) system.

from here

If it cannot expand and the container is totally rigid (this is a totally hypothetical container as nothing is totally rigid) then the water would eventually freeze solid with the solid being compressed to the volume of the container. At exactly what temperature, and by implication pressure, this would happen I couldn't say as I don't have access to compressibility data for water.

209.9 MPa

Over 30,000 psi.

what tyres for 30 000 psi?

what tyres for 30 000 psi?

Ice tyres, natch.

Does a variation on Boyle's law apply?

No that's for gases and I'd say the university report quoted by mrmichaelwright is far more likely to be correct than I am as I was extrapolating from my limited knowledge of the thermodynamic properties of water.

it would remain a liquid.

interestingly, this can be observed in a somewhat risky phenomenon, by putting bottles of beer in a freezer, and forgetting about them, most of them will freeze, and/or crack the glass.

but occasionally, one will not freeze, and upon opening, instantly freeze and shatter the glass.
i think the bottle has to be 100% free of dust inside for it to work?

can work at the other end too, if you microwave pure water (distilled) in a clean mug, until its past boiling point but not boiling, and then throw a pinch of salt at it, it can explode as the salt hits it.

from my limited understanding of the above i think it would only remain liquid until -21.985°C

it possibly wouldn't be an issue unless you removed all the trapped gases from the water first and completely filled the safe. Otherwise it wouldn't cause a problem. Are safe doors watertight too?

I'm not clear why you mention dissolved gasses – how are they relevant, apart from lowering the melting point very slightly as all dissolved substances do ? Pressure lowers the melting point of water – that's why ice is slippery

that was my understanding as well but the article i posted states that even ice skating does not alter the melting point enough to melt the ice through pressure so that may not be strictly true sfb.

Of course the article may be complete tosh.

I remember seeing photographs of an demonstration where ice within a thick steel ball was frozen. Bits of steel were found in the wall!

That'll be 'water' was frozen rather than 'ice' before the STW pedants arrive 🙂

I'm pretty sure that SFB is correct. When you ski and snowboard you are actually riding on liquid water, not snow. This layer of water is probably no more than a few hundred molecules thick but it is liquid none the less. It's the reason that when it's really cold (-30/-40C) that snow become sticky as the pressure that it applied by you isn't enough melt the extremely cold snow.

mmw – take an icecube and crush it in your teeth carefully and controlled – you can melt the ice away far faster than if you just hold it in your teeth with no pressure. While not conclusive, I'd expect I create as much pressure with my skates as I could with my teeth.

midgebait – sounds about right, a car engine typically compresses to about 700psi, one can only imagine what 30,000psi would do 🙂

coffeeking/fishin, one atmosphere of pressure relates to an increase in freezing point of 0.007 degrees C, not sure what the pressure under skis is but i doubt it is significant enough to cause regelation. Skating perhaps though at the very point of the blade enough pressure is applied

again, this is based purely on 'internet knowledge' ™

if the pressure under skis is enough to melt snow then wouldn't you just sink if you stood still 😆

That is how it works. It's the reason why skis/boards don't (or shouldn't) have a smooth base. The texture on the base helps the water flow out from beneath the board/ski. Remember very little of the available area of skis/boards is actually in contact the snow.

hmm, i see what you say

An average contact spot size of 110 ?m, and a relative real contact area of 0.4% [between ski and snow] has been found.

that is a quote from the abstract of a paper on the subject.

interesting stuff, i like learning smarts.

Of course the article may be complete tosh.

correct 🙂

one atmosphere of pressure relates to an increase in freezing point of 0.007 degrees C

uh, increasing the pressure lowers the freezing point of water…

yeah my bad, i actually typed 'decreases the' but changed it. in my defence i haven't had my full quota of coffee yet and am still in my dressing gown 🙂

and i'm just as inclined to have faith in complete tosh from other parts of the internet as i am in some of the tosh you talk on here 😉

it boils, trust me, I've just done it!

and i'm just as inclined to have faith in complete tosh from other parts of the internet as i am in some of the tosh you talk on here

it's seems your scepticism is justified according to wiki:
"Until recently, it was widely believed that ice was slippery because the pressure of an object in contact with it caused a thin layer to melt. For example, the blade of an ice skate, exerting pressure on the ice, melted a thin layer, providing lubrication between the ice and the blade. This explanation is no longer accepted. There is still debate about why ice is slippery"

actually, I wonder if wiki is right on this…

hmmm

the plot thickens

Not sure now, but they use to pressure test alloy cylinders with water as it would just crack, as opposed to explode.

mmw – take an icecube and crush it in your teeth carefully and controlled – you can melt the ice away far faster than if you just hold it in your teeth with no pressure. While not conclusive, I'd expect I create as much pressure with my skates as I could with my teeth.

for gods sake buy some sensodyne first though

The phase diagram below (from here) shows what this is all about. This shows the phases or physical states of Water at different temperatures (in kelvins 273 is zero centigrade) and pressures.

I'm not going to repeat what it says on the website above, but the answers to all your questions are there. I used to know this, but my physics masters was about 13 years ago, but just recently I was called on to examine some freeze thaw failures and had to learn all this again, water is very strange stuff..

Is there a point to the question this thread presents?

thats a great graph toys.

I think I almost understand it, but why does it seem to imply that H20 sublimates at low pressures?

Umm no implication, it does sublime. I'm not sure that there are ever atmopheric conditioons on earth where this would happen – for example the pressure on Everest is approx 30Kpa (sea level its 101kPa) which is above the sublimation pressure shown on the phase diagram.

Edit – there are very low pressures at higher altitudes down to 1 Kpa so in theory it could happen in the earths atmosphere – but this is a bit outside my sphere of knowledge so i cant really comment – what happens at high altitude is influence by other stuff as well. I'm not a climatologist..

wow I didnt know that.

Is that to do with partial pressures n stuff?

EDIT: BTW what do the states 7, 8, 11 and 10 represent?

i looked that up earlier after talk of 'ice 5 etc'

wiki – http://en.wikipedia.org/wiki/Ice#Phases

Yes "partial pressures n stuff" is related. States 7.8.10 and 11 are explained in the link above. It all to do with the molecules of water finding favourable energy configurations in the way they pack as the temp reduces and/or pressure increases.