Why hot water freezes faster

[Itoero]

It looks like hot water freezes faster then cold water.https://en.wikipedia.org/wiki/Mpemba_effect#Suggested_explanations

Is it possible that due to the heat, watermolecules have more energy to form the hydrogen bonds in ice?

[Suzie]

Hot water does not freeze

[Strange]

10 hours ago, Suzie said:

Hot water does not freeze

That is either very funny or scarily pedantic, I'm not sure which!  

 

On 25/11/2018 at 8:19 PM, Itoero said:

Is it possible that due to the heat, watermolecules have more energy to form the hydrogen bonds in ice?

I'm not sure energy needs to be provided to cause hydrogen bonds to form. If anything, the higher temperature (and speed of the molecules) would break the bonds. Which is, I assume, part of the reason why ice melts and water boils.

[Suzie]

1 minute ago, Strange said:

That is either very funny or scarily pedantic, I'm not sure which!

 

I suppose it depends upon what one considers hot, but since water is no longer liquid at 28 to 32 degrees depending on the dissolved mineral content, and at 212 degrees it begins to turn into vapor, the definition of hot as observed by the human is anything over body temp 98 degrees and boiling.  Water at this temp does not freeze, thus anyone who observes it freezing faster then water at below this temp is observing an anomaly in need of investigation.

[Strange]

6 minutes ago, Suzie said:

Water at this temp does not freeze, thus anyone who observes it freezing faster then water at below this temp is observing an anomaly in need of investigation.

OK. But water at any temperature above 0ºC does not freeze. It has to cool to freezing point before it freezes. The observation is that hot water can cool to freezing temperature faster than cold water (the Mpemba effect - see link).

As far as I know, this has still not been fully explained. It may be that there are multiple factors involved.

On 25/11/2018 at 8:19 PM, Itoero said:

Is it possible that due to the heat, watermolecules have more energy to form the hydrogen bonds in ice?

So one of the explanations does suggest that higher temperatures could create more of the types of hydrogen bonds that can act as nucleation centres:

Quote

Tao and co-workers proposed yet another possible explanation in 2016. On the basis of results from vibrational spectroscopy and modeling with density functional theory-optimized water clusters, they suggest that the reason might lie in the vast diversity and peculiar occurrence of different hydrogen bonds. Their key argument is that the number of strong hydrogen bonds increases as temperature is elevated. The existence of the small strongly-bonded clusters facilitates in turn the nucleation of hexagonal icewhen warm water is rapidly cooled down.^[2]

(From your link)

[Itoero]

3 hours ago, Strange said:

On ‎25‎/‎11‎/‎2018 at 9:19 PM, Itoero said:

 

So one of the explanations does suggest that higher temperatures could create more of the types of hydrogen bonds that can act as nucleation centres:

Maybe its due to conservation of energy. When you 'instantly' cool hot water so it freezes then the potential/kinetic energy of the hot water body has  no time to be dispersed in the environment and is conserved in the water body.  Due to the cooling/freezing potential/kinetic energy  changes into potential/electric energy which forms electrostatic attraction which creates hydrogen bonds. Is this possible?

 

3 hours ago, Suzie said:

4 hours ago, Strange said:

 

I suppose it depends upon what one considers hot,

Isn't water described as being hot, when it feels hot?  It's an interpretation.

[tinkerer]

11 hours ago, Itoero said:

Maybe its due to conservation of energy. When you 'instantly' cool hot water so it freezes then the potential/kinetic energy of the hot water body has  no time to be dispersed in the environment and is conserved in the water body.  Due to the cooling/freezing potential/kinetic energy  changes into potential/electric energy which forms electrostatic attraction which creates hydrogen bonds. Is this possible?

 

Isn't water described as being hot, when it feels hot?  It's an interpretation.

"Hot" water might be considered if the water's "hydrogen" content consists entirely of Tritium!

[swansont]

12 hours ago, tinkerer said:

"Hot" water might be considered if the water's "hydrogen" content consists entirely of Tritium!

No, not so much.

[dimreepr]

On 12/4/2018 at 4:04 PM, Itoero said:

Maybe its due to conservation of energy. When you 'instantly' cool hot water so it freezes then the potential/kinetic energy of the hot water body has  no time to be dispersed in the environment and is conserved in the water body.  Due to the cooling/freezing potential/kinetic energy  changes into potential/electric energy which forms electrostatic attraction which creates hydrogen bonds. Is this possible?

2

I suspect its to do with evaporation...

Edited December 5, 2018 by dimreepr

[Itoero]

1 minute ago, dimreepr said:

On ‎4‎/‎12‎/‎2018 at 5:04 PM, Itoero said:

 

I suspect its to do with evaporation…

Maybe it's a mix of several factors.

 

[dimreepr]

1 minute ago, Itoero said:

Maybe it's a mix of several factors.

 

Maybe, but evaporation is a prime suspect.

[Itoero]

20 minutes ago, dimreepr said:

Maybe, but evaporation is a prime suspect.

this is what Wikipedia says: The evaporation of the warmer water reduces the mass of the water to be frozen. Evaporation is endothermic, meaning that the water mass is cooled by vapor carrying away the heat, but this alone probably does not account for the entirety of the effect.

[tinkerer]

On 12/5/2018 at 8:51 AM, swansont said:

No, not so much.

Yeah, 7.5 Kev average, Beta Particles, so "hot" is semantic.........just tryin' to be smart.......

Tritium illuminated wristwatches are widely available on the 'net. Had one long ago, but he "went out" on me. Had a ghastly glow to it. Now, watching Radium Emanation (Radon) gas accumulate and waft away from a sample of Radium would be a real "kick". Better than liquid Helium climbing the walls of a tumbler even.

Edited December 7, 2018 by tinkerer

[Itoero]

On ‎5‎/‎12‎/‎2018 at 4:23 AM, tinkerer said:

Hot" water might be considered if the water's "hydrogen" content consists entirely of Tritium!

When you heat water to maybe 100°C, you don't change the atomic structure.

[swansont]

8 hours ago, Itoero said:

When you heat water to maybe 100°C, you don't change the atomic structure.

"Hot" is sometimes used as a reference to something that is radioactive. It was a pun.

[Itoero]

7 hours ago, swansont said:

"Hot" is sometimes used as a reference to something that is radioactive. It was a pun.

Can you create real radioactive water? I mean pure water, without an impurity.

[swansont]

21 minutes ago, Itoero said:

Can you create real radioactive water? I mean pure water, without an impurity.

If it has tritium in it, that would be radioactive water.

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

(You could also potentially use a radioactive Oxygen isotope, but since there aren't any isotopes with a half-life longer than about two minutes, it's not really feasible)

[tinkerer]

On 12/7/2018 at 11:08 AM, Itoero said:

Can you create real radioactive water? I mean pure water, without an impurity.

"Pure water" is in a way, an elusive substance, since to qualify as "pure" it must have a Ph = 7.00 and contain no dissolved solids, regardless of whether those do not change the Ph. Distilling of water produces "pure" water, but only so long as it is done under a vacuum. As soon as a water surface is exposed to air, it absorbs CO2, which drives it's Ph down below 7.0. Thus, those who preach use of distilled water in their automobile engines, model steam boilers, and the like, while not maintaining that the Ph non-acidic by increasing it via alkaline addition, do the many forum-goers, model-makers and such a disservice. 

Heavy Hydrogen, known as Deuterium, contained in minor amounts in natural waters, is not radioactive; it contains one neutron per atomic nucleus. Tritium, sometimes "very heavy Hydrogen", is quite scarce, is radioactive, emitting Beta through it's decay process, which results in it's becoming He-3, Helium-3, which is not radioactive.

[Rabiye Baştürk]

Enthalpy values for each temperature value are seen by looking at the enthalpy tables used in thermodynamics. The heat taken or given (Q = m.Cp.T) is directly proportional to the temperature difference in the substance. Therefore, the warmer substance tends to cool down faster.

[Strange]

2 hours ago, Rabiye Baştürk said:

Enthalpy values for each temperature value are seen by looking at the enthalpy tables used in thermodynamics. The heat taken or given (Q = m.Cp.T) is directly proportional to the temperature difference in the substance. Therefore, the warmer substance tends to cool down faster.

If you have two containers, one at 20º and one at 25º then, obviously, the second one will, initially cool faster. However, by the time it reaches 20º it will be cooling at the same rate as the one that started at 20º. So this cannot explain why the hotter one could freeze more quickly.

[QuantumT]

The Mpemba effect seems to have been debunked in 2016: https://www.nature.com/articles/srep37665

 

Edited July 28, 2020 by QuantumT

[Strange]

21 minutes ago, QuantumT said:

The Mpemba effect seems to have been debunked in 2016: https://www.nature.com/articles/srep37665

Good find.

[swansont]

They debunked something, but it wasn’t the Mpemba effect. The original observation was about a hot liquid freezing faster than a cool one, and this article limits itself to cooling.

Also, they fall into the Mythbuster trap - that because they couldn’t replicate an effect with poorly defined initial conditions, that the myth is busted, rather than admitting that they haven’t explored all of the possible situations. It’s tied in with “X can happen” vs “X must happen”. Only the latter can be excluded by such attempts at replication

[Externet]

Is there any relation of this claimed Mpemba thermal behavior with efficiency of melting ice on a windshield preferred done with cold water than using warn water ?

[swansont]

1 hour ago, Externet said:

Is there any relation of this claimed Mpemba thermal behavior with efficiency of melting ice on a windshield preferred done with cold water than using warn water ?

I don’t see how. AFAIK that’s so you don’t crack the windshield