Question on Ice

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Gerhard Kemmerer

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A journey into ancient science.

All about the nature of matter, starting with this simple science mystery.

Why does hot water freeze faster than cold water?

Firstly, what does science say about it?
 
Gerhard Kemmerer said:
A journey into ancient science.

All about the nature of matter, starting with this simple science mystery.

Why does hot water freeze faster than cold water?

Firstly, what does science say about it?
Click to expand...

With no facts or references to back it up....

As water freezes it expands. As water is heated it also expands. Should water be heated just enough that it expands near to, but less than the volume of frozen water, there might be a case for it requiring less added energy to cause the water to form the molecular lattice present in its frozen state. It could be that the energy needed to expand is not required and the energy to arrive at the molecular arrangement present in ice, is less than what would be required otherwise.

IOW It might be that you have to excite water molecules enough to allow them the freedom to arrange into a molecular lattice associated with ice.

Completely off the cuff guess.., assuming that there is any situation where it might be true.
 
As the wiki mentions, putting a film of oil on top of water also slows cooling, so that adds a bit to the theory that since warmer water will rise to the top through convection, cooler water will be more likely to form a top layer of ice and possibly insulate further cooling.

But it's also mentioned that there's a lot of factors to consider, as well as clarification of what "freezing" means. First to 0 degrees, first to form a coat of ice, first to freeze solid? All different.

It's a great question, obviously, but since the mention of some science seemed to discourage the OP...
 
origin said:
Hot water does not freeze faster than cold water.
Click to expand...

[chuckle] oh no..... yep you are right there is nothing to discuss...

typical Origin reaction:
wiki said:
The effect is named after Tanzanian Erasto Mpemba. He first encountered the phenomenon in 1963 in Form 3 of Magamba Secondary School, Tanganyika when freezing ice cream mix that was hot in cookery classes and noticing that they froze before cold mixes. After passing his O-level examinations, he became a student at Mkwawa Secondary (formerly High) School, Iringa, Tanzania. The headmaster invited Dr. Denis G. Osborne from the University College in Dar Es Salaam to give a lecture on physics. After the lecture, Erasto Mpemba asked him the question "If you take two similar containers with equal volumes of water, one at 35 °C (95 °F) and the other at 100 °C (212 °F), and put them into a freezer, the one that started at 100 °C (212 °F) freezes first. Why?" only to be ridiculed by his classmates and teacher [read: teacher as Origin]. After initial consternation, Dr. Osborne experimented on the issue back at his workplace and confirmed Mpemba's finding. They published the results together in 1969.[4]
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when it would be so easy to just do a simple experiment for yourself ...
 
OnlyMe said:
With no facts or references to back it up....

As water freezes it expands. As water is heated it also expands. Should water be heated just enough that it expands near to, but less than the volume of frozen water, there might be a case for it requiring less added energy to cause the water to form the molecular lattice present in its frozen state. It could be that the energy needed to expand is not required and the energy to arrive at the molecular arrangement present in ice, is less than what would be required otherwise.

IOW It might be that you have to excite water molecules enough to allow them the freedom to arrange into a molecular lattice associated with ice.

Completely off the cuff guess.., assuming that there is any situation where it might be true.
Click to expand...

I like the fact that you are thinking and not just parroting, and I like your answers, they are related and very close to the answer I have,

but according to the high minders, I am just trolling and don't know anything, so I'll stick to the most skeptical idea, of Origin, and say that it cannot be proven and science has no answer therefore nobody can know or should know, and they are mental if they claim to.
 
Gerhard Kemmerer said:
No you can't do that, it must come from the university or some lab with a panel of unwashed nerds.
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so a Tanzanian form 3 student happens to notice something unexplained by physics and is ridiculed...as not being qualified enough to observe something that some one else has missed or chosen to ignore?

So typical..eh what!!
Possibly because it [the facts of observation] automatically impinges on the much revereed modelling of so many more articulate and qualified physicists.
 
Rhaedas said:
As the wiki mentions, putting a film of oil on top of water also slows cooling, so that adds a bit to the theory that since warmer water will rise to the top through convection, cooler water will be more likely to form a top layer of ice and possibly insulate further cooling.

But it's also mentioned that there's a lot of factors to consider, as well as clarification of what "freezing" means. First to 0 degrees, first to form a coat of ice, first to freeze solid? All different.

It's a great question, obviously, but since the mention of some science seemed to discourage the OP...
Click to expand...

That's wiki, but what about you, aren't you allowed to have your opinion? I guess that's why it is so unacceptable to you over a person who does have their own mind. What do you do with people like that? Run them down, intimidate them, call them names, call them stupid and mental, is that how it is?

Are you under some kind of social duress to do so? It seems that way.
 
Nonsense. If you expect ideas to be tested by the lab, you expect them to be tested by peers as well. No one likes to be laughed at or ridiculed- I don't either. But Science is about testing ideas.
Put them forth to be tested. But complaining that they fail the tests is nonsense. A real scientist gets back to work and tries to more accurately model the hypothesis, not demand that others just "trust" him about his idea.
 
The best explanation I've seen is quite easy to understand - it involves dissolved gasses. Most people understand that anything dissolved in a solute depresses it's freezin point, thus causing the solute to freeze slower. And the same people also understand that cold water contains far more dissolved atmospheric gasses than does hot water which has had them driven out.

Another contributing factor is the considerable increase in vapor pressure in the case of hot water. That naturally leads to faster evaporation - which in turn results in less water to freeze.

Those two things taken singulary or together would appear to be all that's needed to explain it.
 
Read-Only said:
The best explanation I've seen is quite easy to understand - it involves dissolved gasses. Most people understand that anything dissolved in a solute depresses it's freezin point, thus causing the solute to freeze slower. And the same people also understand that cold water contains far more dissolved atmospheric gasses than does hot water which has had them driven out.

Another contributing factor is the considerable increase in vapor pressure in the case of hot water. That naturally leads to faster evaporation - which in turn results in less water to freeze.

Those two things taken singulary or together would appear to be all that's needed to explain it.
Click to expand...

A reasonable and correct answer, but not quite enough difference between the hot and cold water.

Perhaps a combination of all the above factors...?
 
Gerhard Kemmerer said:
A reasonable and correct answer, but not quite enough difference between the hot and cold water.

Perhaps a combination of all the above factors...?
Click to expand...

What??? Can you not read?? Even in the quote you provided it clearly shows that I said "together." And that's quite enough difference, thank you for nothing.
 
Read-Only said:
What??? Can you not read?? Even in the quote you provided it clearly shows that I said "together." And that's quite enough difference, thank you for nothing.
Click to expand...

All the above factors of what others posted.

Less water to freeze due to evapouration? The difference is too slight, nevertheless a good point. The experiment works the same in sealed containers.

But there has not yet been any agreement among yourselves as to whether hot water freezes faster or not.

There is no hard evidence, not that I care for that.
 
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