What freezes faster in an ice tray, cool or hot water?

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The discussion centers around the debate on whether hot water can freeze faster than cold water, known as the Mpemba effect. Participants note that while cold water typically freezes faster under normal conditions, hot water can sometimes freeze more quickly due to factors like evaporation, convection currents, and the removal of dissolved gases. The cooling process of hot water involves losing mass through evaporation, which can lead to a net loss of heat energy, potentially allowing it to freeze faster under specific circumstances. However, all other conditions being equal, cold water is generally observed to freeze faster because it does not need to cool down before freezing. The conversation also touches on practical experiences and experiments, with some participants suggesting that the results can vary based on factors such as volume, pressure, and surface area. Overall, while the Mpemba effect is acknowledged, the consensus leans towards cold water freezing faster in typical scenarios.
  • #31
BobG said:
You missed the point.

Not really.
 
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  • #32
Its pretty nice reading this, though it has been some years back...i have my views here too.


you all correct, but on normal circumstances or conditions, the cold water will freeze first. On experimental conditions, some variables has to be fixed. the hot water will freeze firstly.

Certain conditions has to be met, for the hot water to freeze first ; volume, pressure, atmospheric temperature, and also the surface area of the water exposed to the atmosphere. This has to be equal for the both variants.

You could experiment this again LURCH
 
  • #33
megashawn said:
I have to agree with Fz and Phobos



I mean, is it really that hard to try this yourself?

If you do the problem yourself, you will most likely find that the cold water freezes faster. If you conclude that "cold water freezes faster than hot water," you are then incorrect.

If you repeat the experiment millions of times under different circumstances, you will find that hot water sometimes freezes faster.

Of course you could continue doing experiments, making hypothesis, and testing the results and possibly come to the true solution by re-deriving the laws of physics...

but wouldn't it just be easier to ask someone else who already knows the answer? That's clearly the more efficient way to find the truth...so there's nothing wrong with asking on a forum.
 
  • #35
To put a slightly different twist on it, my father was head of maintenance at a college and remarked on several occasions that hot water pipes always froze before cold water pipes. He's no longer living and I never questioned him about it but I suppose it's possible the cold water was being used more than the hot water allowing it to cool to freezing sooner, or then again not.
 
  • #36
This thread appears to have more lives than Joan Collin's career!

Zz.
 
  • #37
Something slightly interesting...
My roomie decided to steal some of my vodka and replace it with water. I keep my vodka in the freezer though. The first time he did this it was pretty obvious when I came home and found vodka slush in the bottle. The second time though the vodka looked fine until I poured it. Suddenly there were ice crystals (kinda like snow flakes) in the glass as I poured the vodka. And when I agitated the bottle it turned into a thick slush. If I left it sitting in the freezer after that it returned to a purely liquid state eventually. Annoying but interesting.
 
  • #38
My neighbor's son tried this experiment a few years ago. He heated the water in his mothers coffee maker...then placed the hot water...still in the glass coffee pot...in the freezer.

You know the rest...inconclusive results to the experiment..due to an unforeseen variable.
 
  • #39
TheStatutoryApe said:
Something slightly interesting...
My roomie decided to steal some of my vodka and replace it with water. I keep my vodka in the freezer though. The first time he did this it was pretty obvious when I came home and found vodka slush in the bottle. The second time though the vodka looked fine until I poured it. Suddenly there were ice crystals (kinda like snow flakes) in the glass as I poured the vodka. And when I agitated the bottle it turned into a thick slush. If I left it sitting in the freezer after that it returned to a purely liquid state eventually. Annoying but interesting.

A lot of people store their Absolut and Stoli in the freezer.
 

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