Hot water vs cold (freezing)
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Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
Hot water vs cold (freezing)
I was told the other day that hot water freezes faster than cold water. I tried to figure out why, but the person didn't really know the whole concept. My guess is it's wrong because either way, the temperature has to hit 32 before it'll freeze...and I assume the colder water would get to 32 before the warmer water would....
It came up because of some heat pipes in my house that we were surprised didn't freeze. I said it was probably because there was hot water going through it most of the time (for oil heat) so it didn't freeze.
Anyone have any knowledge on the subject?
It came up because of some heat pipes in my house that we were surprised didn't freeze. I said it was probably because there was hot water going through it most of the time (for oil heat) so it didn't freeze.
Anyone have any knowledge on the subject?
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Joined: May 2002
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From: Northwest Fl
I have heard the story plenty of times, but find it very hard to beleive. To make something colder, cold is not put into it, instead heat is removed from it. If it is already hot, that is just more heat that has to be removed.
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From: Hendersonville, TN
I've heard this for years and don't see, from a physics standpoint, how it would be possible. I agree with your thoughts. Less change has to be affected upon the colder water to bring it down to 32 deg. People who argued the point always said "your hot water pipes freeze up in the winter more often than your cold". I always attributed this to the fact that you might not be flowing the hot water, like for a shower or washer for hours before you go to bed, but you'll run the cold to flush the toilet or get a drink right up to bedtime. Therefore the water in the hot pipes sits stationary in the pipes longer, giving it more time to freeze. I'd really love to get the REAL answer to this and the science behind it which ever way it goes (especially if I'm wrong, because I just don't get it).
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From: Hendersonville, TN
Originally Posted by Huntsman
I have heard the story plenty of times, but find it very hard to beleive. To make something colder, cold is not put into it, instead heat is removed from it. If it is already hot, that is just more heat that has to be removed.
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From: covington wa.
I've heard the samething that warm water will freeze faster because of the molecular make up or lack of in the water,
what that is i dunno.
what that is i dunno.
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Joined: May 2004
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From: Abilene Kansas
it has to do with molecules and there activity, when the water is warm the molecules are spread out and if you subject them to freezing weather they are liable to freeze faster because they are spread out... its all in in the molecular form of the compound
Matt
p.s. i hate chemistry!
Matt
p.s. i hate chemistry!
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I'm a mechanical engineering graduate student and I heard about this in my heat transfer class. It doesn't make sense and its very illogical but it happens. It doesn't happen all the time but in certain conditions. The best way I can explain is the heat transfer sorta builds momentum and is cooling at a much faster rate than normal due to the large temperature difference. Sorta like starting the quartermile going 20 instead of 0.
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From: Plano, Tx.
I don't understand it either, but I've seen it work. when I was younger and it got cold I tried to pour water on the concrete outside so it'd freeze and we could play on it. but the ground wasn't quite cold enough and the water would run off before it froze. so I put hot water on it and it froze fast enough. it does work, I tell you what.
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Joined: Aug 2004
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From: Michigan
You know, when I was in elementary school I remember learning something along these lines. Our teacher posed the question, "Which freezes faster, hot or cold water?" and by her facial expression, I figured the answer must be hot because she had that "I'm going to fool you!" look so I said hot. Then I guess she explained how I was wrong...
I've had thermo but we didn't talk specifically about hot or cold water freezing first... maybe at certain temperatures it will change state quickly from liquid to solid? I wish I had my book because it has a graph and I could tell you what temps...
I've had thermo but we didn't talk specifically about hot or cold water freezing first... maybe at certain temperatures it will change state quickly from liquid to solid? I wish I had my book because it has a graph and I could tell you what temps...
Last edited by D-ranged2.5; Jul 29, 2005 at 10:46 AM.
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Post Fiend
Joined: Nov 2001
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From: Topsfield, MA
I heard something about it having to do with the oxygen content in the water....
I'll have to google search "Mpempba effect" when I get a chance.
I think this winter I'm going to have to put a pot of hot and cold water outside and see what happens
I'll have to google search "Mpempba effect" when I get a chance.
I think this winter I'm going to have to put a pot of hot and cold water outside and see what happens
Last edited by MustangGT221; Jul 29, 2005 at 01:39 PM.