Talk:Supercooling

Supercooling and glass transition

There was an incorrect information about the possibility of supercooling dow to the glass transition. Liquid water, for example, cannot be supercooled down to its glass transition, but only down to its crystal homogeneous nucleation temperature at ~150 K at atmosferic pressure. By fast cooling it is possible to avoid the crystall nucleation, going directly to the glass phase below ~136 K. I also added a reference (Debenedetti and Stanley) with all these informations. (Giancarlo Franzese, http://www.ffn.ub.es/gfranzese/) 16 Oct 2005.

Amorphous?

I doubt whether supercooled compounds solidify into amorphous solids in general. Water in any case will always freeze to the Ih phase under atmospheric pressure, though the crystals will be quite small after such a rapid freezing process. -- Hankwang 19:48, 20 Mar 2004 (UTC)

The general statement is that aliquid will either crystallize or solidify into an amorphous solid. As an example [ortoterphenyl] (popular among experimental glass physicists) will often crystallize spontaneously at very low temperature (AC

Which liquids can be supercooled

It is correct that many liquids cannot be supercooled... Well in principle you can call this an experimental problem or a problem of choosing the right time scale and examining a small system, but in many cases the [metastable] supercooled state is just not meaningful, because it does not last very long. (AC)

Supercooled Water

In the temperature interval from -39 C to -120 C water freezes almost instantaneously. However in the temperature interval between -120C and -138C it is possible to have a stable supercooled phase. Below -138C the water becomes solid again. Many researchers believe that this is a glass transition. I have heard people claim that recent neutron scattering experiments suggest that there is a real phase transition at -138C (rather than a glass transition), but I know too little about that. (AC)

www.digibio.com/archive/RedHerring_com-Why_water_is_weird.htm

I wish people would check the quality of their comments, like using real words and spaces n' stuff. —Preceding unsigned comment added by 24.22.79.74 (talk) 16:39, 25 November 2008 (UTC)

Dynamic arrest -> glass transition

I think that it is better to use the word [glass transition] instead of dynamic arrest

Glass is supercooled

The article contains an inaccuracy: If you chill a supercooled liquid below the glass transition temperature, then it becomes a disordered solid, but it is still supercooled. Therefore it would be better to write

"Supercooling is the process of chilling a liquid below its freezing point, without crystalization."

Contradiction?

From the article:

Its glass transition temperature is much colder and harder to determine, but studies estimate it at about 165 K (−108°C).[2] Glassy water can be heated up to approximately 150 K (−123°C).

How can glassy water only be heated up to 150 K if it can form at the higher temperature of 165 K?--kenb215 01:26, 9 December 2005 (UTC)

It still says that - is it right? And if so what does it mean (as Ken's question above)? Thanks. Naomhain (talk) 11:43, 9 February 2012 (UTC)

The application

Despite the reference, the application listed in the article is an example of exothermic crystalization from supersaturated solution, not supercooling. Supercooling is defined as cooling a fluid below its freezing point. This example is cooling a liquid below the crystalization point of a solute, not below the solution's freezing point.

The reference is filled with inaccurate uses of terminology. The reference confuses being liquid with being in solution. The heat of crystalization of NaAc is what causes the jump in temperature. Given a crystalization seed, the solution in the heat bags would begin to crystalize at 130F (it doesn't freeze at 130).Dusty78 20:18, 1 October 2006 (UTC)

This article isn't clear to a reader not au fait with super cooling. A bit of fleshing out may make it a bit more approachable.

One application of supercooling

http://www.youtube.com/watch?v=SfkHS_58yvs

"Hulk looks at beer... Hulk thinks really cool... Hulk wants beer NOW!"

This could be a very nice wedding prank. lol --Wxyrty 23:05, 19 March 2007 (UTC)

Anybody know how they chill it to get it to solidify like that? (It also looks like sodium acetate coming out of a supersaturated state.) Arc88 21:58, 15 April 2007 (UTC)

If cooled at a rate of the order of 1 million kelvins per second

This is really fast - I expect the article meant to say "milli-kelvin", but i'm not sure so I didnt change it. —The preceding unsigned comment was added by 24.68.227.168 (talk) 07:36, 22 April 2007 (UTC).

THIS IS FAKE

unless prooven i do not believe because most supercool experiments i have viewed look like they have has sodium asitate dissolved into the water... attempt to proove me wrong —The preceding unsigned comment was added by 84.66.129.246 (talk) 22:51, August 21, 2007 (UTC)

Melting point or freezing point ?

The first line says "Supercooling is the process of chilling a liquid below its melting point..." but the next line says "A liquid below its freezing point will crystallize ...". IMHO for a liquid, the 'freezing point' is applicable. If there are no objections, I'll change the 'melting point' to 'freezing point' -- WikiCheng | Talk 04:47, 27 August 2007 (UTC)

This is incorrect--the melting point and freezing point can happen at different temperatures. See for instance Figure 8 in Zachariassen and Kristiansen 2004 Cryobiology--pure water will melt at 0 degrees and freeze at -17 C or so. Kemarshall (talk) 19:56, 26 September 2022 (UTC)

I changed it as the article melting_point clearly mentions "When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point." -- WikiCheng | Talk 04:53, 27 August 2007 (UTC)

i want some 1 to tell me how to do this all i know is that its kool —Preceding unsigned comment added by 75.108.40.89 (talk) 22:20, 13 November 2007 (UTC)

Superheating citation

Why is a citation needed in the part about superheating (under "Description" at the end) when there is a link to another adequately cited Wikipedia page describing the phenomenon itself? Or is the missing citation referring to another part of the paragraph? --The Sphinx (talk) 21:34, 6 January 2008 (UTC)

"Can be supercooled"

There is an unclarity both in this article and in Water about the definition of freezing point for water, and also a misunderstanding regarding melting/freezing point.

1. What IS the freezing point for water? what are the 'certain conditions' in which water can supercool, besides the lack of nucleation points? Aren't these conditions more accurate for defining that the freezing point of water is indeed minus 42 degrees celcius?
2. As we can see in water, the freezing point isn't always the melting point. In Wikipedia, Freezing point refers to Melting point which seems incorrect.

I'm not a chemistry guy and want to know whether these can be corrected in Wikipedia. Gil_mo (talk) 18:14, 4 February 2008 (UTC)

Melting and freezing point are statistically defined. That is, they refer to the phase transition between most probable macrostates in a thermodynamically random sample. Mathematically, they occur at the same temperature due to thermodynamic laws. If you control the randomness (by cooling really fast), you can achieve less-likely macrostates, and I believe supercooling is an example of this phenomenon. SamuelRiv (talk) 17:54, 6 February 2008 (UTC)

Mmm. I dunno. We got taught that although melting point is well defined, because of the above couple of points, "freezing point" is in fact not well defined, period. Gzuckier (talk) 19:38, 6 February 2008 (UTC)

These articles are garbage. What about supercooling helium? No word at all. —Preceding unsigned comment added by 207.108.42.8 (talk) 15:41, 11 March 2009 (UTC)

In Fish

I'm no expert; this is all new information to me. It all makes sense to me up the point where it says "because they must come into contact with ice nuclei (otherwise they would freeze immediately , since they are only supercooled.)". It seems to me that if these fish were to come into contact with ice nuclei, they would freeze immediateley. The above statement in the article sounds (to me) like it is saying that if these fish _don't_ come into contact with ice nuclei, they will freeze. If I'm correct then the above should probably read something like this: "These fish must stay far below the water's surface because if they come into contact with ice nuclei (which are found closer to the surface of the water) they will freeze immediately." SCooley138 (talk) 18:57, 23 January 2012 (UTC)

supercooling contradicts hydrogen bonding

Ok, I know the subject line is a little sensational, but when I found out about supercooling I found a contradiction in my understanding of how water becomes a solid. I thought that water became ice when the temperature was so low that the molecules didn't wiggle enough to break hydrogen bonding. But, that doesn't make sense when you think about supercooling because the supercooled water must be cold enough to form hydrogen bonds, therefore making it technically ice by my previous definition. Obviously supercooled water is not ice.

Also, I thought ice had more volume than water because the lattice structure formed when the H2O molecules are hydrogen bonded has more empty space than if the molecules were not hydrogen bonded. Does supercooled water have the same level of hydrogen bonding as ice? Would that mean that supercooled water has greater volume than non-supercooled liquid water? — Preceding unsigned comment added by 204.77.163.4 (talk) 15:15, 5 April 2012 (UTC)

Where does the heat go?

A large amount of heat needs to be removed from a liquid to solidify it. Where does it go at the instant subcooled water turns into ice? Or had it been removed if the liquid lingers a while at the freezing point before continuing to get even colder? (How I now wish I had taken P-Chem in college!) And is the heat of fusion different if the liquid turns into a glass? Casey (talk) 15:28, 1 December 2012 (UTC)

The heat has already been removed by cooling the liquid below its melting point. The lower the temperature achieved before solidification, the more heat has been removed. When solidification occurs, normally only a part of the body of liquid solidifies. The solidification releases heat, which warms the remaining liquid until the entire mixture reaches the melting point. At this point, solidification stops (more precisely, stability is reached, the rate of freezing equals the rate of melting). Depending on the level of cooling reached before solidification occurred, the mixture may still appear liquid, with only a few crystals formed (for example ice-needles in water), or it may be slushy, or appear mostly solid, with only a little liquid left between crystals. Complete spontaneous solidification only happens when enough heat has already been removed to compensate the heat of fusion for the entire mass. The way I understand the article, for water this would be around 225K (-48°C).

No, when supercooling, in other words when not solidifying, the temperature does not "linger at the freezing point". The temperature simply continuously drops. The "lingering" occurs when the liquid does solidify, where the heat of fusion supplies the energy needed to maintain a constant temperature even though energy is being removed by cooling.

My understanding of "turning into a glass" is that a liquid continually moves slower and slower (becomes more viscuous) until it simply stops, with no sudden changes involved. Since there is no sudden change, I imagine that there is no "heat of fusion" in this case. However, looking at just one of the article's references (Molinero 2011, "Structural transformation in supercooled water controls the crystallization rate of ice"), it would not surprise me if this assumption is wrong and the truth is much more complicated.

--RainerBlome (talk) 08:23, 11 September 2017 (UTC)

So, this is why when I leave beer in the freezer too long, it instantly turns to slush once I pop the top?

Interesting...I had speculated that it was because popping the top dropped the pressure, which cooled it slightly by decompression, which brought it below its freezing point. I did think it suspicious that the beer should so often happen to be exactly just above freezing temperature, and the way it rapidly turned to slush didn't quite seem to be the way it ought to behave just from dropping suddenly below freezing. Too consistent and homogeneous. Also, the fact that if it was really cold, even jostling or shaking it would cause it to freeze even when still sealed. Other times, I open it, and it wouldn't freeze for several minutes. I take a few sips, and suddenly on the next sip, I'd find "beer slushy"! This explanation makes much more sense...I assume that it's like superheating, and the liquid remains until something disturbs it, causing tiny seed ice crystals to form, which initiate a chain reaction which freezes the liquid?.45Colt 07:09, 16 March 2015 (UTC)

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Vocabulary

The article should note the terms "solid" and also "freezing", as these are also "crystalline states". (noting not all substances are considered crystalline when solid, says wikipedia) — Preceding unsigned comment added by 72.219.204.96 (talk) 17:46, 1 November 2015 (UTC)

The article now mentions both solid and freezing point (which leads to freezing) in the introduction.--RainerBlome (talk) 14:40, 11 September 2017 (UTC)

hmmm What something is missing here?

The article does not mention that not all solids (glass aside) are considered crystaline when solid, or whether these substances have a "super cooling" laboratory measurement differing from random seeded samples.

Nor does the article list which elements (let alone if any compounds) DO super-cool. I see no chart of supercooling temperature of each element. Please entertain.

— Preceding unsigned comment added by 72.219.204.96 (talk) 17:46, 1 November 2015 (UTC)

I do not understand your first sentence. "Not crystaline when solid" is a definition of glass, so why "glass aside"? It is true that not all solids are crystals. When you asked, the article did already mention glass and glassy water and that under certain circumstances "an amorphous (non-crystalline) solid will form". If you still consider something missing, please suggest a concrete addition.

What do you mean by "super cooling laboratory measurement differing from random seeded samples"?

Regarding your request for entertainment: The article does mention that water does super-cool. Feel free to supply a chart. If you don't know how to edit, just leave the references here.

--RainerBlome (talk) 15:16, 11 September 2017 (UTC)

about Wikipedia calling super-cooling "less related

The heat of fusion article calls super-cooling "more random and less related so not listed".

It seems to me that super-cooling is a more pure measurement. In adding a "seed" one does not know the value or nature of that's seed's creation or how to "add it in". Knowing that standard lab measurements are tainted by impure circumstances leads me to beleive wikipedia (see heat of fusion article) should not be saying it is "less related fusion and less used" a property: it's probably a more important property (excepting for material science applied science). And it makes one wonder percentage wise what seeding impurity steals from the measurement / process, the adding what has already overcome latent heats and how much.

One would wonder if heat of fusion is also commonly / likewise tainted by having "a seed in the sample never crystalized which begins fusion early" (i know compounds under microscopes are often very hap-hazardously arranged)

I would think crystaline struture may be related should be mentioned as effect on "super cooling" (also atomic arrangement, radii, electro negativity) .

I'll now think of "super cooling value" as "true heat of crystallization" and the other as a "tainted value". Although am less sure using the value would be useful to determine other values or properties, since so much data exists upon what causes the phenomena already.

— Preceding unsigned comment added by 72.219.204.96 (talk) 17:46, 1 November 2015 (UTC)

Article contradicts itself - Anima

First the articles says cuper cooling is a property of total and homogenous atomic crystallization without aid of pre-seeding; by laboratory purity.

The article then says that "cell protection" is a form of super-cooling and related it to nearly un-describable impurity rather than purity - which if you don't mind my saying: appears to be lowering of freezing point (which is Absolutely unrelated with super-cooling, and so does not belong in the article or topic)

— Preceding unsigned comment added by 72.219.204.96 (talk) 17:46, 1 November 2015 (UTC)

isotope Question

Are different isotopes of the same substance also super-cooling? The CRC book says differnt isotopes of the same element may have very different properties from the "stable isotope (assumed if not mentioned)". I think crystalline structure (or at least fine angles) and other properties are not predictable when not "the stable most used isotope". — Preceding unsigned comment added by 72.219.204.96 (talk) 17:46, 1 November 2015 (UTC)

My guess is that different isotopes of the same chemical element have the same properties when it comes to super-cooling. Which "CRC book" are you referring to? I do not understand "assume if not mentioned", can you please be clearer? Isotopes do not differ in electron configuration. Since electron configuration is what determines crystal structure, different isotopes have the same crystal structure. Regarding differences in "fine angles", the nature of crystals is that precise discrete angles are maintained regardless. For an ordinary crystal, there is no such thing as a "slightly differing angle". The possible angles are effectively determined by the mathematics of periodic 3D structures. Yes, quasicrystals exist, which may allow for more variation, but my guess is that they are not relevant for supercooling. Which "other properties" are you referring to?--RainerBlome (talk) 07:33, 24 October 2017 (UTC)

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"In animals" section

This revision by an anonymous user on 2017-03-25 placed a paragraph into the "In animals" section that is unacceptable for a Wikipedia article. I don't know if he is right or wrong, I'm just a passing editor, but at the very least he could have used a dubious template instead. EpsilonCarinae (talk) 05:44, 12 January 2018 (UTC)

I removed the commentary. It definitely doesn't belong in the article itself. As far as their objection, I don't think they're correct. The Antifreeze proteins article states that these don't simply depress the freezing point like antifreeze for your car, but actually inhibit the growth of nucleation sites, which is consistent with achieving a supercooled state. dimhue (talk) 06:49, 16 March 2018 (UTC)

I also reworded the first line in that section, which someone changed the references to freezing point depression. Based on the description of the processes, I am certain it's describing a supercooled state and not freezing-point depression, because the liquid is clearly below its freezing point if ice crystals start to form. — Preceding unsigned comment added by Dimhue (talk • contribs) 06:57, 16 March 2018 (UTC)

Supercooling in spaceflight

Supercooling or super-chilling is also mentioned in spaceflight applications, although there it simply means "cooling down fuel to just above the freezing point" (as opposed to cooling it down just below the vaporisation point.) Should this find mention here? Here are some uses of the terms: https://qz.com/627430/the-super-chill-reason-spacex-keeps-aborting-launches/ https://www.techbriefs.com/component/content/article/tb/pub/techbriefs/machinery-and-automation/30024 --Syzygy (talk) 15:36, 16 September 2020 (UTC)