# Is there a limit to how fast water can freeze? **URL:** \ **Category:** Factual Questions\ **Created:** [July 23, 2016, 6:59pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698 "2016-07-23T18:59:21Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 23, 2016, 6:59pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/1 "2016-07-23T18:59:21Z")
See query. I thought of it today sweating away, watching, waiting, waiting…agonizing seconds for my room temperature soda to get colder (please hurry) in my glass full of ice. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [July 23, 2016, 7:21pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/2 "2016-07-23T19:21:51Z")
I say a tentative yes there is a limit. Once a layer of ice forms between the water and whatever is cooling it. The ice is acting as a solid insulator/thermal conductor. For a given temperature between the two sides, only so much heat will flow through, this value determined by the thermal properties of the ice. The cold side has a limit. Absolute zero. Therefore you can only “pump” heat through the ice so fast to cool the water side. And as the ice gets thicker, that value will continue to decrease. The actual speed of a near absolute zero freezer and an ice cube tray would be interesting to know… ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 23, 2016, 7:26pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/3 "2016-07-23T19:26:58Z")
I was actually thinking of something like maybe approaching an _exo_thermic reaction when atoms do their phase change stuff. Mental image (obviously of layman): everybody (atoms) shuffling into alignment like in musical chairs, and all that elbowing must itself create some heat. Crystallization is neat, let alone phase change. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [July 23, 2016, 7:31pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/4 "2016-07-23T19:31:11Z")
Speaking of which…I managed to super cool a whole case of water bottles recently. People were wondering why I was out in the garage laughing with joy like a school kid yelling “cool as shit!” as each one magically turned solid over about 3 seconds when I picked it up. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [July 23, 2016, 7:31pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/5 "2016-07-23T19:31:54Z")
I’d imagine that the fastest possible freezing would occur in supercooled liquid water upon nucleation. Water can remain in liquid form to -48degC at standard pressure. > **[Supercooling](https://en.wikipedia.org/wiki/Supercooling)** > > Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid below its freezing point without it becoming a solid. It achieves this in the absence of a seed crystal or nucleus around which a crystal structure can form. The supercooling of water can be achieved without any special techniques other than chemical demineralization, down to −48.3 °C (−54.9 °F). Droplets of supercooled water often exist in stratus and cumulus clouds. An aircraft flying throu Animals ... ---
**Author:** ![Kedikat](https://avatars.discourse-cdn.com/v4/letter/k/ed655f/32.png) [@Kedikat](https://boards.straightdope.com/u/Kedikat)\ **Post date:** [July 23, 2016, 7:33pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/6 "2016-07-23T19:33:59Z")
Freezing involves the water molecules actually locking onto each other to form a solid lattice. Water temperature can go a long way below 0C, yet still not freeze. A large volume of super cooled water can freeze almost instantly, once the first ice crystals form. So I suppose the fastest water can freeze, is limited by how fast the molecules can physically move into the ice crystal formation. Very fast under the right conditions. Best way to make fast ice, is a shallow metal tray. Like a cookie sheet. Heat will conduct fast off the large surface area above and below. When done, you can shatter the sheet of ice into nice thin pieces with large surface area to cool your drink. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [July 23, 2016, 8:24pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/7 "2016-07-23T20:24:16Z")
In a practical sense … no, water can appear to freeze instantly with the human senses. Obviously it’s not instant in the strictest definition, but close enough to make no difference. I would offer **freezing rain** as an example. As it is falling through the air column, the liquid water temperature drops just below the freezing point. When it strikes an object, it pretty much all turns to ice upon this contact and sticks to whatever it hit. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [July 23, 2016, 8:36pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/8 "2016-07-23T20:36:48Z")
> [@Leo\_Bloom](#): > > I was actually thinking of something like maybe approaching an _exo_thermic reaction when atoms do their phase change stuff. > > Mental image (obviously of layman): everybody (atoms) shuffling into alignment like in musical chairs, and all that elbowing must itself create some heat. > > Crystallization is neat, let alone phase change. Yup, freezing is exothermic, albeit not because of elbow friction! If you are trying to reduce the temperature of water, the freezing process slows that down temporarily. If you keep steadily extracting heat energy from liquid water, the temperature of the water drops steadily down to zero C, then stays constant for a while at zero C while it freezes, because the freezing process releases energy. Once freezing is complete, the temperature resumes dropping. > **[Enthalpy of fusion](https://en.wikipedia.org/wiki/Enthalpy_of_fusion)** > > In thermodynamics, the enthalpy of fusion of a substance, also known as (latent) heat of fusion, is the change in its enthalpy resulting from providing energy, typically heat, to a specific quantity of the substance to change its state from a solid to a liquid, at constant pressure. > The enthalpy of fusion is the amount of energy required to convert one mole of solid into liquid. For example, when melting 1 kg of ice (at 0 °C under a wide range of pressures), 333.55 kJ of energy is absorbed with ... > [@](#): > > …energy is released from a liquid when it freezes, because the molecules in the liquid experience weaker intermolecular forces and so have a higher potential energy (a kind of bond-dissociation energy for intermolecular forces)… ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [July 25, 2016, 12:22pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/9 "2016-07-25T12:22:34Z")
> [@billfish678](#): > > I say a tentative yes there is a limit. > > Once a layer of ice forms between the water and whatever is cooling it. > > The ice is acting as a solid insulator/thermal conductor […] This. However, this limit doesn’t necessarily have a limit. I mean, if you get to control the geometry of the problem, you can spread the water very thin, and do so on an object that is practically completely cold, i.e. near absolute zero. They make (or made) some superconductor out of amorphous metal this way, IIRC. They have a very cold copper disk spinning fast, and spray the molten metal on the edge of the disk. It spreads out quite thin. The thermal path is therefore very short and freezing happens very fast. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [July 25, 2016, 12:30pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/10 "2016-07-25T12:30:49Z")
What happens to a single H20 molecule when it drops to 0C? Is it just colder than it was before, or does something else about it change? ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [July 25, 2016, 12:38pm UTC](https://boards.straightdope.com/t/is-there-a-limit-to-how-fast-water-can-freeze/760698/11 "2016-07-25T12:38:17Z")
> [@TriPolar](#): > > What happens to a single H20 molecule when it drops to 0C? Is it just colder than it was before, or does something else about it change? Basically nothing. The individual atoms might be vibrating within the molecule a little less than they were before, but that’s a continuous process — it’s not like there’s a qualitative change in this behavior at 0C. The phase transition is inherently a phenomenon that happens because you have a large number of molecules that can assemble themselves into a more ordered state.