hot water freezes more quickly than cold water -- WHY?

[Darren Dirt]

apparently SCIENTISTS STILL DO NOT KNOW WHY!
http://m.torontosun.com/2012/06/27/why-does-hot-water-freeze-faster-than-cold


http://en.wikipedia.org/wiki/Mpemba_effect

[Mr. Analog]

The main problem is that there are a lot of variables at work, like convection.

[Thorin]

Hey, there's a $1,500 reward for figuring this out?

[Mr. Analog]

Hey, there's a $1,500 reward for figuring this out?

Whoa, is it offered in the United States? If so: God did it.

[Thorin]

You didn't read that first link, did you?  The theory that god did it for yucks has already been floated, and has been marked as not precise enough to get the bounty.

[Mr. Analog]

You didn't read that first link, did you?  The theory that god did it for yucks has already been floated, and has been marked as not precise enough to get the bounty.

No LOL

Actually I'm pretty sure it's Thetans^TM anyway, first John Travolta's haircut face combo and now hot water freezing before cold water.

[Tom]

Huh. I had thought it was proven that it really doesn't freeze quicker, its just that the volume of water goes down enough to freeze the water quicker since there's less of it.

[Thorin]

Darren, we might disagree sometimes, but at least I read your posted link.  And this was/is an interesting thread.

Tom, that theory has been floated as well but isn't the provable cause.  See the Wikipedia link in the first post.

I thought it was the lack of frozen top layer in the hot water that caused it, but it's not one single simple thing like that.

[Darren Dirt]

Huh. I had thought it was proven that it really doesn't freeze quicker, its just that the volume of water goes down enough to freeze the water quicker since there's less of it.

My gut instinct (when in a sciencey mood) is that it's something to do with the molecules, their arrangement ... but does anyone know if this phenomena is just in WATER (H20) or is it in a lot of other liquids?


Because water is pretty wonky when it comes to what it does/doesn't do at certain temperatures and temperature changes, compared to most other substances in liquid form. Have the Experts tried to understand that stuff first i.e. analyze "a few frames within the whole moving picture" to then figure out why the overall film plays out the way it does? ... and is the freezing effect pretty much the reverse of http://en.wikipedia.org/wiki/Leidenfrost_effect ?

[Tom]

Huh. I had thought it was proven that it really doesn't freeze quicker, its just that the volume of water goes down enough to freeze the water quicker since there's less of it.

My gut instinct (when in a sciencey mood) is that it's something to do with the molecules, their arrangement ... but does anyone know if this phenomena is just in WATER (H20) or is it in a lot of other liquids?


Because water is pretty wonky when it comes to what it does/doesn't do at certain temperatures and temperature changes, compared to most other substances in liquid form. Have the Experts tried to understand that stuff first i.e. analyze "a few frames within the whole moving picture" to then figure out why the overall film plays out the way it does? ... and is the freezing effect pretty much the reverse of http://en.wikipedia.org/wiki/Leidenfrost_effect ?

Wonky indeed. I think its the only liquid that expands when it transitions to a solid. Normally the molecules would get closer together as they slowed down, and they do, up till a point, then everything expands again.

[Darren Dirt]

expands when it transitions to a solid. Normally the molecules would get closer together as they slowed down, and they do, up till a point, then everything expands again.