Answer This And Win £1,000: Why Does Hot Water Freeze Faster Than Cold Water?

Psst! Want £1,000? All you have to do is explain this curious property of water: why does hot water freeze faster than cold water.

The Royal Society of Chemistry is backing the prize:

"Ice cream makers and bartenders alike use the fact that hot water freezes more quickly than cold water every day in their work, but no one really knows why it works. The problem has been around for millennia, with philosophers such as Aristotle and Descartes pondering over it.

"But this effect was reintroduced into the scientific world in 1968 by Erasto Mpemba, a young inquisitive student in Tanzania during a lab session.

"Erasto questioned a teacher on why ice cream froze more quickly when it was boiled, and was quickly told that he was wrong and had probably imagined it. It was only when the teacher performed the experiment himself that he noticed this unusual phenomenon.

"Since the discovery of the effect, scientists have been trying to find out why the phenomenon occurs but remain divided as to what the answer is. It seems that there are lots of possible answers but a conclusive explanation hasn't been produced yet.

Link - via metafilter

Think that's the only weird thing about water? Check this out: 5 Really Weird Things About Water | Image: Defrosty the Snowman Ice Cubes

I'm a big support of supporting everything with science but screw science now. Not everything can be explained with a scientific phrase. I live in canada and after coming home from a long cold day i like to put my hands under some hot tap water because it so quickly makes it warm whereas when I put it under cold water, nothing really happens because my hands are already cold but slowly it will get colder like that. This in my opinion is the exact same thing as hot water freezing faster than cold, because its a bigger transition therefore somehow it changes faster. Where little changes occur slower. You can counter me and say we have nerves and so it makes no sense since water doesn't have nerves but a part of me thinks that water has some kind of nerve like things that allow the same thing to happen.
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Mexicant1: I lol'd! Nice.

I'll never forget, a girl in my 6th grade class did a science fair project on this topic, and without even hearing her out, our teacher publicly humiliated her by saying that it was impossible for hot water to freeze faster than cold, and that she was failing her project without discussion. Poor girl - I hope that nasty teacher sees this article!!
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It's because the demon that keeps water liquid goes to sleep when you heat it up...by the time it wakes up, it's already half frozen and he just goes back to sleep again.
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its because water evaporates due to a difference in vapor pressure. when you put hot water in cold freezers, there is a high vapor pressure gradient and you get lots of steam off the surface. this draws huge amounts of energy fromt he water. Also, a classic practice differential equation, the rate at which heat convectss (such as into the air) is proportional to the difference in temp between the mediums. hotter water will loose heat faster than cooler water. these two effects are the main drivers in why hot water freezes faster
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Here's what the Straight Dope had to say on the subject: cold water freezes faster than any kind of hot water, but really hot water freezes faster than somewhat hot water.

http://www.straightdope.com/columns/read/422/which-freezes-faster-hot-water-or-cold-water
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Wow, looks like there are a bunch of commenters in that "5 weird things" post who are apparently smarter than the RSC and ready to collect the £1,000. Also enjoyed the "debate" there about homeopathy.

Proof that even on an awesome blog like Neatorama one can't avoid the idiot comments.
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