Hot Water Freezes Faster when making ice cubes

[Demonaut]

anyone ever heard of this before?

[wtmusic]

1. No it doesn't

stop that!! :crazy:

[progmom]

2. it's a lie!

A lie, I tell you!

A vast, right-wing conspiracy.

[underpants]

3. Complete BS

Water freezes at 32 degrees F why in the world would 80 degree water cool to 32 faster then 40 degree water?

[Nevernose]

4. Yes.

My mother's new husband is a chemist or chemical engineer or something like that, and he swears that this is true and can back it up with all sorts of scientific jargon. I, unfortunately, am more suited for discussing the works of George Bernard Shaw, and am therefore completely incapable of even repeating what he said, other than to say that his answer would be "yes."

[redqueen]

6. It's something to do with evaporation... I think.

I really should work on improving my memory.

[DS1]

9. I've heard of it described as momentum of temperate change

:shrug:

[redqueen]

16. Don't go gettin' me all worked up

with your geek speak.

:P

[oneighty]

17. Yes

Evaporation --cools the water AND reduces the volume to be cooled to freezing. One assumes that the hot water and cold water containers start with equal volume.

Also warm water has less dissolved gases to act as an insulator.

There are plenty of explanations on the internet.

180

[underpants]

18. On the same site as the alien autopsy ??

:eyes:

[redqueen]

19. Yay for smart!

The cubes end up smaller as a result, but they do freeze faster.

[underpants]

20. No they don't

[Kellanved]

21. IIRC no

AFAIR it is because the crystals grow faster in the water that used to be hot, under very special circumstances (after cooling below 0°C, that is).
Evaporation has a hand it getting to the freezing point, though.

[redqueen]

5. Yes I have.

IIRC, I've seen it proven.

:shrug:

[proud2BlibKansan]

36. So have I

Many times. It's really true.

[jandrok]

7. Yep. Here's a couple of links that explain how it works.

http://math.ucr.edu/home/baez/physics/General/hot_water.html

http://library.thinkquest.org/C008537/cool/freeze/freeze.html

Lots of experimental support for the phenomenon.

[DrGonzoLives]

8. Wrong

Newton's Law of Cooling says no.

[Wilber_Stool]

10. Have a look

at this:

http://www.straightdope.com/classics/a2_098b.html

[Pirate Smile]

11. Yes, look at this:

Dear Yahoo!:
Does hot water really freeze faster than cold water?
Grace
Kinston, North Carolina

Dear Grace:
The phenomenon you describe is one of modern science's few remaining mysteries and the source of much debate in certain circles. Given the right set of conditions, hot or warm water can freeze faster than cooler water.
This strange phenomenon was described by the likes of Aristotle, Bacon, and Descartes, yet is named after the Tanzanian high-school student who demonstrated it in 1969. The Mpemba effect only occurs under very specific sets of conditions and is still not completely understood.

Though the effect has been reproduced successfully in a number of experiments, no one can say with certainty why it happens due to the great number of variables involved. However, it is generally believed some combination of factors, such as evaporation, convection, conduction, and supercooling, may account for the Mpemba effect.

You'll be glad to know that however mysterious the phenomenon is, the Mpemba effect is put to good use by many ice-cream makers, who use warm milk instead of cool to help their ice cream freeze more quickly.

You may also be interested to know that for such a seemingly simple substance, water is surprisingly complex, and its behavior is poorly understood. The Mpemba effect is just one of 38 anomalies of H2O.


Email this page - View most popular
http://ask.yahoo.com/ask/20030930.html

[Worst Username Ever]

12. Yes, I've heard if is because of the added minerals, etc in hot water.

But that doesn't make a lot of sense to me, since as the hot water cools, it is going to hit the room temp that the tap water would have been anyway.

[VTMechEngr]

13. Heard it and Its false.

Old wives tale. I will add that if you add other conditions like air circulation and such, its possible, but its from the other added stuff, not from water itself.

[underpants]

22. Welcome to DU

Richmond here.

Nice website -from your profile

Oh yeah almost forgot GO HOOS!

[VTMechEngr]

24. Just remember one thing

When UVA asks Hoos your daddy? Why its a Hokie of course. :)

[underpants]

26. In the immortal words of "Ron Mexico"

How much is Marcus's bail THIS TIME?!?!?

:bounce:

[VTMechEngr]

27. touche

But UVA is still Tech's Bitch. :headbang:

and
Thanks for Getting us in the ACC. :toast:

[SmokingJacket]

14. Go try it out!

I can't think of an easier experiment to do.

[City Lights]

15. Hot water makes more solid ice cubes (less bubbles) than cold water.

Don't know whether they actually freeze faster.

[zbdent]

23. Simple -

try it.

My money's on the cold water.

(I actually tried this as a teen.)

[Waistdeep]

25. A Definitive Answer

http://math.ucr.edu/home/baez/physics/General/hot_water.html

Short summary: Warmer water can, under some circumstances, freeze faster than cold. However, it's quite difficult to produce the precise circumstances in which it does. It can be for a simple a reason as more of the warmer water evaporated, hence making the smaller quantity easier to cool.

Shorter summary: It can, but rarely. It is certainly wrong to say "Hot water freezes faster than cold".

Real short summary: Almost never and I bet you can't do it under controlled circumstances.

[Lisa0825]

29. exactly...

and more info from The Straight Dope. http://www.straightdope.com/classics/a2_098b.html

when water cools down from near boiling to the freezing point, as much as 16 percent evaporates away, compared to 7 percent for water at 160 degrees. The smaller the amount of water, of course, the faster it freezes.

In addition, the water vapor carries away a certain amount of heat. To test this theory, Jearl covered his lab beaker with Saran Wrap to prevent water vapor from escaping. The freezing rate difference was greatly diminished. Conceivably convection (motion within the water) also plays a role.

Fascinating as all this no doubt is, all it basically proves is that very hot water freezes more slowly than very VERY hot water. The ordinary fumbler in the fridge, on the other hand, is dealing with temps more like the ones I was measuring, in which case cold freezes faster than hot.

[radwriter0555]

28. nah. total myth. just apply critical thinking. the water STILL has to cool

down to a specific temp before it reaches the freezing point. Using hot water slows the process even further.

[ProfessorGAC]

30. Heard It. Totally False

No matter what, the sensible heat contained within the water must be removed by cooling before the freezing point can be attained. The enthalpy of fusion is then overcome at that point, not before.

So, any excess heat takes time to be dissipated. The warmer the water, the longer this takes. Hence, cooler water always hits the freeze point sooner, and freezes first.

End of story.
The Professor

[bertha katzenengel]

31. Hell yeah. I've heard of that before. How can it be true?

I am willing to be convinced. Just as I am willing to be convinced of the existence of the God of the Bible.

[Robb]

32. From plumber dad:

He says the only reason it appears to, from time to time, is that most hot water heaters in homes will have a certain amount of particulate matter built up in them; the particulates present in hot water from the tap can speed the freezing process.

Also, many people don't keep their hot water heaters cranked to maximum temperature (plumbers and their families tend to). When the curve describing the temperature drop from "hot" to 32 degrees intersects with the impurity of the water from the heater's tank, presto, hot water wins. :)

[oneighty]

33. Another factor

Hot water has less dissolved gasses so when it freezes in the pipe (As compared to cold water saturated with atmospheric gasses) It will expand more and cause the hot water pipe to fracture sooner than the cold water buffered with dissolved gasses.

So many people observe the hot water pipe to freeze before the cold water pipe because the hot water pipe fractures and sometimes the cold water pipe does not.

If one puts boiling water in a Styrofoam cup and cold water with an equal volume the hot water will freeze first due to evaporation.

I saw it on the internet. I am not a researcher. Hee hee hee.

180

[wtmusic]

34. Hey, anybody want to invest in my cold fusion machine?

This time it's for REAL. Honest.

[Demonaut]

35. hey I have a perpetual motion flashlight for sale too