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 Data
That Guy
Registered: 08/12/08
Posts: 4,035
Loc: Southwestern US 
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 Hot water freezes faster than cold water? 
#720241 - 03/09/14 07:15 PM (10 years, 8 months ago) |
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I've heard this argument in my neck of the woods for years. As an engineer, I have my own opinions...but I would like to hear everyone else's opinion on the matter...as well as any explanations for those opinions.
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“The Universe is under no obligation to make sense to you” -NDT
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mjmihalov
Stranger
Registered: 01/25/13
Posts: 800
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Re: Hot water freezes faster than cold water? [Re: Data]
#720243 - 03/09/14 07:36 PM (10 years, 8 months ago) |
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Cold water freezes faster.
"The Mpemba effect, named after Erasto Mpemba, is the assertion that, in some circumstances, warmer water can freeze faster than colder water. Although there is evidence of the effect, there is no agreement on exactly what the effect is and under what circumstances it occurs. There have been reports of similar phenomena since ancient times, although with insufficient detail for the claims to be replicated."
So I guessss maybe under a certain set of circumstances it can be possible, but usually it's not.
Edited by mjmihalov (03/09/14 07:44 PM)
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 volcomstoner
Just one more xanax
Registered: 03/30/09
Posts: 4,956
Loc: Gaybec
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Re: Hot water freezes faster than cold water? [Re: mjmihalov]
#720249 - 03/09/14 08:02 PM (10 years, 8 months ago) |
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I have always heard hot water freezes faster. i have no explination as to why, and Ive never thought enough about it to do any research 
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Data
That Guy
Registered: 08/12/08
Posts: 4,035
Loc: Southwestern US
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Re: Hot water freezes faster than cold water? [Re: mjmihalov]
#720251 - 03/09/14 08:13 PM (10 years, 8 months ago) |
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Anybody else wanna take a shot on the other side?
I am about 99.999997% sure that cold water freezes faster in all situations achievable under atmospheric pressures.
I know people who fill ice trays with hot water all the time, and they swear it freezes faster. The only way I could really see this happening is if there is significant evaporation of the water in the trays prior to reaching lukewarm/cool temperatures, thus leaving less liquid water to cool down to freezing (less total heat to remove from the liquid water portion). However, the energy removed during evaporation has to go somewhere, and the freezer still has to remove that energy...so IMO (without doing the thermo calcs) this evaporation would have little/no effect on the required time to freeze the liquid portion.
Idk...just wanted to see how many people have run into this argument, or if I just live in a section of the country with a particularly low average IQ.
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“The Universe is under no obligation to make sense to you” -NDT
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KaptKid
Spaced Pirate
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Loc: Bright Side of the Sun
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 Re: Hot water freezes faster than cold water? [Re: Data]
#720252 - 03/09/14 08:20 PM (10 years, 8 months ago) |
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I heard hot water freezes faster because of the tiny air bubbles in it.
I not an engineer so I'm just repeating what I was told as a young kid.
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Child of the 60's, Tripping ever sence.
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volcomstoner
Just one more xanax
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Loc: Gaybec
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Re: Hot water freezes faster than cold water? [Re: KaptKid]
#720253 - 03/09/14 08:21 PM (10 years, 8 months ago) |
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Quote:
KaptKid said:
I heard hot water freezes faster because of the tiny air bubbles in it.
:science:
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mjmihalov
Stranger
Registered: 01/25/13
Posts: 800
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Re: Hot water freezes faster than cold water? [Re: KaptKid]
#720254 - 03/09/14 08:22 PM (10 years, 8 months ago) |
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Hot water does not usually freeze faster.
I am suprised everyone didn't know that.
Test it out.
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Farmer Joe
Registered: 09/03/09
Posts: 1,707
Loc: USA
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Re: Hot water freezes faster than cold water? [Re: Data]
#720255 - 03/09/14 08:23 PM (10 years, 8 months ago) |
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I've had this come up in conversation a few times myself. I have a buddy that claims it works. Never tried it myslef. I've always kinda wondered if it were true or not.
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Picklez
Registered: 04/20/08
Posts: 17,919
Last seen: 10 years, 5 months
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Re: Hot water freezes faster than cold water? [Re: Data]
#720256 - 03/09/14 08:23 PM (10 years, 8 months ago) |
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cold water freezes faster than hot water
I dont see how it could even make sense for it to be the other way around. When you freeze something you are trying to achieve a certain temperature known as "Freezing Point," and the closer you start off to FP the easier it is to achieve FP as long as both samples are held at the exact same conditions.
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mjmihalov
Stranger
Registered: 01/25/13
Posts: 800
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Re: Hot water freezes faster than cold water? [Re: volcomstoner]
#720257 - 03/09/14 08:24 PM (10 years, 8 months ago) |
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Quote:
volcomstoner said:
Quote:
KaptKid said:
I heard hot water freezes faster because of the tiny air bubbles in it.
fixed?
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UltimateDevotion
TwistedByDesign
Registered: 11/23/12
Posts: 5,935
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Re: Hot water freezes faster than cold water? [Re: Data]
#720258 - 03/09/14 08:25 PM (10 years, 8 months ago) |
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Quote:
agmotes165 said:
Anybody else wanna take a shot on the other side?
I am about 99.999997% sure that cold water freezes faster in all situations achievable under atmospheric pressures.
I know people who fill ice trays with hot water all the time, and they swear it freezes faster. The only way I could really see this happening is if there is significant evaporation of the water in the trays prior to reaching lukewarm/cool temperatures, thus leaving less liquid water to cool down to freezing (less total heat to remove from the liquid water portion). However, the energy removed during evaporation has to go somewhere, and the freezer still has to remove that energy...so IMO (without doing the thermo calcs) this evaporation would have little/no effect on the required time to freeze the liquid portion.
Idk...just wanted to see how many people have run into this argument, or if I just live in a section of the country with a particularly low average IQ.
There was some old dudes talking about this exact same thing the other day at work and I'm thinking to myself "no fuckin way does hot water freeze faster than cold water" but have heard peoe
Say this and I think that they're fucking retards for believing what they heard from other retards.
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volcomstoner
Just one more xanax
Registered: 03/30/09
Posts: 4,956
Loc: Gaybec
Last seen: 7 years, 9 days
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Re: Hot water freezes faster than cold water? [Re: mjmihalov]
#720261 - 03/09/14 08:27 PM (10 years, 8 months ago) |
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Quote:
mjmihalov said:
Quote:
volcomstoner said:
Quote:
KaptKid said:
I heard hot water freezes faster because of the tiny air bubbles in it.
fixed?
no, it was actually intentional. That graem just didn't do it justuce
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Data
That Guy
Registered: 08/12/08
Posts: 4,035
Loc: Southwestern US
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Re: Hot water freezes faster than cold water? [Re: KaptKid]
#720262 - 03/09/14 08:27 PM (10 years, 8 months ago) |
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I haven't heard that one before...
I've heard stuff like heat transfer inertia...as in the heat transfer starts out fast because of the larger temperature difference, and it continues to draw heat out at an accelerated rate even after the water cools down to the temperature of cold tap water.
Another explanation I've heard is "It's closer to a phase change".
The rest of the people who have explained it to me say "It works for me everytime" but never seem to have timed it or directly compared a tray of hot water and a tray of cold water.
For all of these explanations...im still 
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“The Universe is under no obligation to make sense to you” -NDT
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Stoneth
D.I.L.L.I.G.A.F.
Registered: 10/06/08
Posts: 25,048
Loc: No where ville, USA
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Re: Hot water freezes faster than cold water? [Re: volcomstoner]
#720264 - 03/09/14 08:40 PM (10 years, 8 months ago) |
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Hot water freezes faster.
It's just fact.
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Picklez
Registered: 04/20/08
Posts: 17,919
Last seen: 10 years, 5 months
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Re: Hot water freezes faster than cold water? [Re: Stoneth]
#720266 - 03/09/14 08:43 PM (10 years, 8 months ago) |
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I am not watching those videos but is it really a fact?
Like hot water vs. room temperature? and how "hot" is the "hot water"
I guess you learn something new every day, even from a bunch of stoners
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mjmihalov
Stranger
Registered: 01/25/13
Posts: 800
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Re: Hot water freezes faster than cold water? [Re: Picklez]
#720269 - 03/09/14 08:45 PM (10 years, 8 months ago) |
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Quote:
Picklez said:
I am not watching those videos but is it really a fact?
Like hot water vs. room temperature? and how "hot" is the "hot water"
I guess you learn something new every day, even from a bunch of stoners
It is a fact that under certain circumstances hot water can sometimes freeze faster than colder water.
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Picklez
Registered: 04/20/08
Posts: 17,919
Last seen: 10 years, 5 months
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Re: Hot water freezes faster than cold water? [Re: mjmihalov]
#720270 - 03/09/14 08:47 PM (10 years, 8 months ago) |
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Learn something new every day.
What are these "circumstances?"
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Stoneth
D.I.L.L.I.G.A.F.
Registered: 10/06/08
Posts: 25,048
Loc: No where ville, USA
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Re: Hot water freezes faster than cold water? [Re: Picklez]
#720271 - 03/09/14 08:50 PM (10 years, 8 months ago) |
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Last time I experienced this first hand was a month or so ago.
It got down to 9f.
I got in the shower to wash my ass, a few minutes in it became a very cold shower.
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Data
That Guy
Registered: 08/12/08
Posts: 4,035
Loc: Southwestern US
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Re: Hot water freezes faster than cold water? [Re: Stoneth]
#720275 - 03/09/14 09:00 PM (10 years, 8 months ago) |
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Quote:
Picklez said:
Learn something new every day.
What are these "circumstances?"
That's the problem, there are no defined circumstances...unless you count modification of an individual body of water's total freezable mass and its heat transfer characteristics through mass loss.
Quote:
Stoneth said:
Hot water freezes faster.
It's just fact.
The first video is interesting, but this can be explained by evaporative cooling of the airborne droplets. The evaporation causes a cooling effect on the droplets, and also results in loss of mass. These smaller droplets (which are now at the same temperature as the larger cool droplets from the "cold water" sample, have less mass to cool below freezing, and better heat transfer characteristics because of the larger surface area/volume ratio. Unfortunately, it does not explain why people claim that hot water in ice trays freezes faster than cold water in ice trays.
The second video is also interesting, but misses a key point. If this is true, it would mean that all liquid water would have a higher freezing point, because the "cold water" would never get to its "cold" state without freezing before it got to that temperature.
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“The Universe is under no obligation to make sense to you” -NDT
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Data
That Guy
Registered: 08/12/08
Posts: 4,035
Loc: Southwestern US
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Re: Hot water freezes faster than cold water? [Re: Stoneth]
#720276 - 03/09/14 09:02 PM (10 years, 8 months ago) |
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Quote:
Stoneth said:
Last time I experienced this first hand was a month or so ago.
It got down to 9f.
I got in the shower to wash my ass, a few minutes in it became a very cold shower.
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“The Universe is under no obligation to make sense to you” -NDT
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