What happens to water if it’s not allowed to expand when frozen? | Hacker News Reader

What happens to water if it’s not allowed to expand when frozen?

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89 pointsandreyf39 comments

Water is not the only substance that expands when frozen.

The following elements expand when frozen: Gallium, Germanium and Plutonium.

There is also a wide range of molecules that expand when frozen. What's really less well known about water is it expands right before it freezes (4C - 0C) which significantly inhibits lakes from freezing in the winter by creating a large boundary layer.

The converse, negative thermal expansion ceramics like zirconium tungstate, are fascinating materials; they shrink when you heat them.

It's all to do with low-frequency vibrational modes, but if I started talking about mode Gruneisen parameters I'd start boring the arse off all of you and, what's worse, giving myself flashbacks...

Wow I did not know there were actually different types of ice. There is even an ice IX which is unfortunately (well, actually, fortunately) not nearly as cool and destructive as the ice-9 imagined by Kurt Vonnegut.

As one of a handful of mineralogists on Hacker News (and I suspect that Timetric's pretty much cornered that market), I'm delighted to see phase diagrams on here!

This stuff is utterly fascinating. OK, I'm biased, I did my doctoral thesis on diffusion networks in silica glass, but things like the ortho/clinopyroxene or feldspar systems - http://en.wikipedia.org/wiki/Feldspar - are just really beautiful.

(I mean, look at it! http://en.wikipedia.org/wiki/File:Albite_-_Crete_(Kriti)_Isl.... Not as spectacular as APoD, OK, but I don't regret my time in science.)

The difference between the types of ice is similar to the difference between graphite and diamond: same atoms, different arrangement and different crystal structures that are thermodynamically favored at different pressures.

Tangentially related: I've heard that if you want to freeze someone with cryogenics, you need to drop the temperature very quickly to far below normal freezing, so that you get a different type of ice crystal. I'm not entirely sure what the difference is (I'm not even sure this is 100% true), but I suspect whatever harm you're avoiding is related to why frozen food doesn't taste as good. If a chemist, biologist, or cryogenist could correct me, I'd love to hear the details.

Alton Brown's explanation on Good Eats of how to get good frozen strawberries effectively said that if you freeze them slowly, you get jagged ice crystals which slice membranes and cause them to turn to mush when you defrost. If you do it quickly it creates smaller, smoother crystals that leave the structure intact.

Yes- larger crystals + expansion --> puncture and break cell walls --> not good when you're defrosted. Tangentially, this is why ice cream cooled with liquid nitrogen is so smooth

ok, where can I try ice cream cooled with liquid nitrogen?

The Fat Duck in Bray, run by Heston Blumenthal -- http://www.thefatduck.co.uk/

Heston is awesome. We just did a series on TV where we made, amongst other things, edible wallpaper as the desert course, so all these celebs were licking the walls...

He also explained (on Peachy Keen) that if you add some sugar (being hygroscopic) to the fruit (making a sugar syrup), the sugar will help hold some of the water in the cell walls helping to reduce the size of the ice crystals.

Over in the cryogenics discussion groups they don't even like you to use the word "freezing". Bad for PR and all. "Vitrification" is the going term.

Great video, but maybe they should have been wearing lab coats. They look like wallstreet CEOs in those suits.

At my office, we're doing "fancy Friday", which is like casual Friday, but, you know, fancy. I've started taking it pretty seriously.

People have noted that when I wear a nice suit, I look far more authoritative. My wife joked that I needed to put a lab coat on over the suit, pin on a police badge, and carry a clipboard. Then everyone would be convinced of my authority.

Pretty much as the Milgram experiment found out - http://en.wikipedia.org/wiki/Milgram_experiment.

All it takes is a lab coat to be perceived as an "authority figure" by most people - with distressing results.

Oh goodness! Oh for heavens sake!

In the phase diagram on Wikipedia, which is more precise, shows a negative slope on the transition frozen-liquid, unlike the sketched version on the second video, which, I guess, is for all other elements. On such a negative slope, if the temperature increases the transition will continue to occur if the pressure decreases.

Isn't this negative slope well in accordance with the fact that water expands when freezing?

Ah, now I understand that glaciers actually are made of a different kind of ice!

I've seen glacier ice on numerous occasions, and it has a very blue tinge, unlike normal ice. I now understand that that is probably one of the other ices that is formed at a very high pressure.

No, glacier ice is blue for the same reason the ocean is blue; ice absorbs similar wavelengths to liquid water.

I think it's more because air bubbles are squeezed out as the glacier moves, making it clearer than fridge ice which usually contains many air bubbles.

http://en.wikipedia.org/wiki/Blue_ice_(glacial)

Pure new snowbanks are blue inside too.

I don't think that's the reason. As far as I know it's just normal ice.

If you put it in container that it can't possibly break, will it not freeze completely?

I understood that it would indeed freeze completely - it would just have a different crystalline structure than regular ice that freezes at room temperature. Some of the molecular configurations result in higher density than liquid water, so it would actually contract rather than expand in those instances.

You can try this at home with a bottle of beer. Put it in the freezer, forget about it (happens to me all the time) and open it. It freezes instantly.

This has to do with dissolved gasses which escape on opening changing the freezing point, not the inability of water to destroy an aluminum can. Freezing water fractures solid rock, creates pot holes in roads, and has no problem breaking a thin aluminum shell.

Interesting, thanks. That won't stop me from putting beer in the freezer though.

Gp ahead, just don't do it with beer bottles. It takes quite an effort to remove all the little shards of broken glass and the fridge smells like beer :)

I've never had that happen, but wouldn't the cap come off first?

Apparently not; I've had a bottle of soda 'sploding in my freezer. I'm guessing that since the bottle's neck is so slim the water there freezes first, effectively "plugging" the bottle.

I think that is right, since the freezing points / boiling points are also influenced by pressure. So when it tries to expand and cannot expand due to an unbreakable container, the pressure increasing substantially, and the respective points also change.

I'm sure if you try to boil water to steam, and keep it in a container that cannot expand, it won't convert completely to steam, since pressure increases its boiling point. With the conversion to ice, I am not exactly sure (something similar happens possibly) just because it is a little atypical in terms of volumes and liquid / solid states. Also, too tired to look this up :)

If you keep increasing the temperature it will eventually all turn to steam, at an extremely high pressure.

"There was a sound like that of the gentle closing of a portal as big as the sky, the great door of heaven being closed softly."

For our next chat we will be discussing the endochronic properties of resublimated thiotimoline...

(Downvote? Really?) http://en.wikipedia.org/wiki/Thiotimoline

Wouldn't the pipe be much more brittle when the co2 was poured on it?

I believe that's true. However, at my parents' cabin in the Rocky Mountains, the pipes still blow if they aren't drained properly (they're at surface level). It's only happened twice that I can remember, but it's quite impressive to see a steel pipe with a crack running the entire length.

Also note the solution is not to insulate exterior pipes as said in the video: insulation without a heat source simply delays the freezing. No, you have to put heat tape around the pipes. Or drain them. Running water is also not a solution - now instead of your pipes freezing, your drain will freeze. My friend the plumber was always gleeful when the newsmen would pass along that old urban legend: a long, profitable night for him, replacing drainpipes in mobile homes!

This is why bricks are not allowed to have bubbles, if some water gets stuck in those in rain and in winter if it freezes we get cracks

A lot of normal building brick is pretty porous, if not protected from getting really wet just before a freeze you get spalling, where the face of the brick flakes off. Brick that is too non-porous on the other hand, like sewer brick, forms relatively weak mortar bonds, which is why it is rarely used in buildings.

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