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Freezing Hot Water vs Cool Water

06/28/2012 12:53 AM

It may not be a new question but this phenomena is said to still boggle human minds:

Why does warm or hot water freezes more quickly than cool or cold water??

Let's hear the answer from the more knowledgeable here!!:) Of course I don't have a clue to that except a vague idea about molecular bondage playing some role in the phenomena? Not sure though,

Likewise another phnomenon comes to my mind which says: Fire can be equally extinguished with cold water or hot water. This is true but I do not know how hot and cold water applies to water in so far as freezing is concerned..??

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#80
In reply to #78
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Re: Freezing Hot Water vs Cool Water

07/02/2012 3:02 AM

This debate has taken off in a fiery manner. This is good. We need such like from time to time. The Mpemba Effect was on our local talk Radio in South Africa a few days ago [Radio 702]. I have had to revise my understanding of this topic following the re-opening of the Mpemba Effect debate.

I am one for practical demos and prototypes. I would like to see whether there might be any point in putting together science experiment kit for investigating such a phenomena. My usual science demo kits have been along the line of problem solving e.g. for finding solutions to oil spills. I use a cat litter box, tap water and some used engine oil. Creative solutions have been found through the application of common old household products such as baking powder and a nylon stocking.

These ones are more practical in nature and also more urgent. But I would also be keen to set up demo kits for something like this freezing issue. The Mpemba effect tackles a problem that lies more within the realm of fundamental physics. This is also relevant and can be equally exciting.

By the way, I have been procrastinating and slacking off with the repair of the rubber seal on my deep freeze. So my refrigerator currently does not freeze effectively. First have to solve this problem.

If there is anyone out there, in the know, please do inform us whether the whole debate on this phenomena has actually been resolved completely. Surely by now some academic spark would have done a thesis on this subject by now. This looks like a Physics post-grad Thesis topic.

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#81
In reply to #80

Re: Freezing Hot Water vs Cool Water

07/02/2012 4:24 AM

The first thing that needs to be established is - is the effect real, in a properly designed experiment? Has this been done?

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#82
In reply to #81

Re: Freezing Hot Water vs Cool Water

07/02/2012 4:44 AM

This last comment by Code Master is short, sweet and to the point ! In my view, this is the best response so far. Indeed, one must clarify this point : Is the effect real ? 2nd point is : To compare 2 sets of experiments under controlled conditions under which all else is exactly the same except for the single difference of one hot and one cold in terms of the starting point for the 2 waters.

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#84
In reply to #80

Re: Freezing Hot Water vs Cool Water

07/02/2012 10:20 AM

This has more the look of a parlor trick, and as I said earlier, the experiment is manipulated to produce un-natural results.

Have at it.

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#85
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Re: Freezing Hot Water vs Cool Water

07/03/2012 2:38 AM

Great way of putting it Lyn. I have learnt "Economy of words" from yourself and Codemaster. Parlour-tricks indeed. I had a suspicion but was not abs sure that it was. Is it definitely the case, as you say, the lab equivalent of a a slight of hand or parlour trick? If it is not then we do indeed have a tricky unsolved problem. If it is correct then we might ask ourselves how might we use such a phenomenon to our practical and economic advantage?

Or are we merely wasting valuable Cr4 Space? Let us be reminded that nature does indeed have a treasure chest of wonderful jewels in the form of unexplored phenomena, materials, devices, and so on. The latest (for a few years now) is to look to Biology to get solutions to practical engineering problems. This is, of course, the approach aptly termed Bio-mimicry. Why spend days pondering over a seemingly shiny object (water freezing a minute or two more rapidly under certain obscure conditions) when the lies a treasure chest of useful solutions elsewhere in nature? Let's call the latter a kind of "fools-gold" in the "nature-mimicry" sense.

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#92

Re: Freezing Hot Water vs Cool Water

07/03/2012 11:57 AM

This is entirely empirical , but I know that if you pour warm water on your windshield to remove frost, it will freeze almost instantly.Using cold water will melt the frost instead.Try it, you will see.As for the explanation of why, that is still a little fuzzy in my mind, but it goes something like this:Water can sublimate, that is, change from a gas to a solid without passing through the liquid state.If there is adequate heat-sinking ability in the surrounding environment,this cooling process occurs so rapidly that the latent heat of condensation and the latent heat of fusion occur simultaneously.This results in a thin layer of ice at the boundary layer on the surface,which is composed of very small crystals of ice,(much smaller than from normal cooling). These small crystals have much more surface area than larger crystals,(which form with the cooler water-to -ice transition, and therefor shed heat much quicker, and therefor can transport heat much quicker from the liquid below, and this heat is emitted into the relatively infinite heat sink surrounding the surface.The end result is that the latent heat of fusion is removed faster from the liquid, and the water freezes quicker than if the temperature of the water was lower to begin with.The cool water does not produce enough temperature differential to initiate the sublimation effect.

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#100
In reply to #92

Re: Freezing Hot Water vs Cool Water

07/03/2012 9:39 PM

A revised version of my theory:

I was using the wrong terminology in my original post.I used "Sublimation" instead of "Deposition' for the phase change of water vapor directly into ice.Sublimation is the opposite effect, where ice is directly changed to water vapor.same amount of energy required, just in opposite direction.()

Hot water has vapor rising from the surface.This vapor is instantly converted to ice by the high differential temperature.(Think:Molecular level) It requires 720 calories/gram to be absorbed by the environment to convert vapor to ice.When the ice is returned to the surface of the water, it requires 80 calories/gram to melt the ice.This heat is radiated into the environment.In this manner, much more heat is removed from the water than if the water is at a lower beginning temperature.There will be a very negligible loss of volume because most of the water vapor is returned as ice.

As the temperature of the water decreases, the vapor decreases, but the small crystals formed by deposition act as seed crystals for further ice formation,which will form at an accelerated rate due to this seeding.There should also be an accelerated emission of heat during this crystallization process.I would love to see an infrared image in real time as this occurs

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#105

Re: Freezing Hot Water vs Cool Water

07/06/2012 9:38 AM

What if the Royal Society was offering a reward to prove that the world was flat. How would the arguments be worded back before the answer was known by all of the world?????

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#106
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Re: Freezing Hot Water vs Cool Water

07/06/2012 9:53 AM

So your position is that the Royal Society of Chemistry falsely believes in the Mpemba Effect?

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#107
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Re: Freezing Hot Water vs Cool Water

07/06/2012 10:01 AM

No not at all. It is just that at todays level of knowledge we are all trying to prove, or disprove the theory. Just as back in the fifteenth century they, with their level of knowledge must have been having the same arguments about the "round world" theory.

As we all gain knowledge, our outlook on things change. At some point in time school children may talk about how way back in the 21 century they still believed that cold water boiled faster, or slower, which ever way it works out to be.

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#108
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Re: Freezing Hot Water vs Cool Water

07/06/2012 10:09 AM

I don't think there is a prevailing theory as to how it works, which is why the Royal Society of Chemistry is offering a reward.

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#111
In reply to #107

Re: Freezing Hot Water vs Cool Water

07/06/2012 10:37 AM

"It is just that at todays level of knowledge "

If one looks at the level of knowledge of the first 10-20 posts this morning you'd swear that the level of knowledge/intelligence was ZERO!

No one asks for help or discussion. They just want us to do their jobs for them.

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#112
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Re: Freezing Hot Water vs Cool Water

07/06/2012 11:03 AM

Yes, I know. I'm glad I am not like that. BTW, could you run to the store for me?

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#113
In reply to #112

Re: Freezing Hot Water vs Cool Water

07/06/2012 11:05 AM

Sure. Gotta take the kids to karate camp anyway. Need a 6-pack?

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#114
In reply to #113

Re: Freezing Hot Water vs Cool Water

07/06/2012 11:13 AM

..and while you're at it have a pee for me on the way past the gents.

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#115
In reply to #107

Re: Freezing Hot Water vs Cool Water

07/09/2012 10:46 AM

'....Just as back in the fifteenth century they, with their level of knowledge must have been having the same arguments about the "round world" theory.....'

.

.

...psst...psst...hey look everyone.

.

Shhhhh....you don't want to startle it.

.

You are lucky; this is very rare.

.

Some people never get to see Irony in the wild. Those people will only know it only by trite examples provided by a mostly forgotten book of literary devices.

You however do not share their fate. You are observing an striking example of wild IRONY in its natural habitat.

.

Isn't it magnificent?

.

Notice how it ridicules 'fifteenth century' 'level of knowledge' for harboring a mistaken belief unwilling to accept the truth (of a round world). This is the process in which the irony is actually creating its own distinguishing features!

.

The statement betrays a greater 'level of knowledge' deficiency concerning the 15th century debate over the round world than could reasonably be noted in nthe 15th century scientific community.

.

You see, the meaningful 'round earth' debate in the 15th century was probably smaller than the same debate is today. People have known the world is round(ish) for at least over two thousand years. Aristotle, Pythagoras, and Eratosthenes all professed belief in a spherical world. Eratosthenes even made a decent calculation of the size of the sphere.

(...now I just hope I didn't miss something previously made note of all of this....making my statement the actual regally unaware wild Irony.)

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#110

Re: Freezing Hot Water vs Cool Water

07/06/2012 10:18 AM

Ok, lets look at it in another way.

Now I'm thinking that this may have a connection here.

Since you can throw boiling hot water in a -20°C cold day such as here, that would create steam/ice crystals, what would happen if the water temperature be say +20°C and then throw it under the same conditions.

With the boiling water having a higher temperature differential, turning into steam prior to freezing would create more surface area to freeze

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#116

Re: Freezing Hot Water vs Cool Water

12/15/2012 8:13 PM

hot water is de-ionized though the heating procees. reseach The univerity of Illinois for the correct infomation.

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#117
In reply to #116

Re: Freezing Hot Water vs Cool Water

12/16/2012 6:27 AM

So how does de-ionization of the water affect the freezing rate?

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