Anomalies of hot water!

[canadianpoet]

I've never tested this, but when I was at school (frighteningly large number of years ago now) my chemistry teacher once told me that if you put 2 bowls of water outside in the winter; 1 with hot water one with cold water, the hot water will freeze quicker than the cold water!

 

Is this actually true?! If so, can someone explain the mechanics behind it. Surely the colder water would freeze first as it's particles have less energy to start with, and so wouldn't take so long to become a solid.

 

On the same theme: if I wash my dishes up with warm water, the water dries faster than if I use cold water. This makes sense, as the particles in the warm water are closer to the evaporation point.

 

So what's the deal with the freezing of cold water - if it is in fact, correct!?

[Gilded]

Heeey... Wasn't there a thread about this some time ago? And even before that one?

[The Rebel]

I've never tested this' date=' but when I was at school (frighteningly large number of years ago now) my chemistry teacher once told me that if you put 2 bowls of water outside in the winter; 1 with hot water one with cold water, the hot water will freeze quicker than the cold water!

 

Is this actually true?! If so, can someone explain the mechanics behind it. Surely the colder water would freeze first as it's particles have less energy to start with, and so wouldn't take so long to become a solid.

 

On the same theme: if I wash my dishes up with warm water, the water dries faster than if I use cold water. This makes sense, as the particles in the warm water are closer to the evaporation point.

 

So what's the deal with the freezing of cold water - if it is in fact, correct!?[/quote']

 

I remember seeing this puzzle on TV once. It waas set as a challenge to the viewers to explain why it happens.

 

I'm guessing its got something to do with the kinetic energies of the hotter molecules being lost a lot quicker by collisions than the slower moving colder water. Some other ideas include the idea that the warmer water sets up convectional currents that allow it to cool quicker.

 

It may be worth trying this at home. Get a couple of containers of water, one hot and one luke warm. Place the two in the fridge/freezer and monitor the temperature changes.

[RICHARDBATTY]

yes its true Its due to the convection of the water. Using the temp difference to drive the circulation and allowing the water to cool evenly. Cold water freezes first at its outer surfaces and the ice then insulates the still liquid water. You can make ice cubes faster this way too, try it.

[jdurg]

In our previous thread it was never conclusively proven. It's a phenomenon that has been shown to happen, but not on all occasions. The 'evidence' that was constantly brought up was not in a 'controlled environment' and there was little to no attempt made to produce the same result over and over and over again. For something to be a fact in science, it has to be repeatable by different people in different parts of the world. Saying that 'I did it, but it doesn't happen all the time' is not proof of anything.

[Externet]

Hi.

It is a common suggestion to get rid of ice on a windshield by pouring cold water on instead of warm; there has to be a relation to the behavior

 

Am from Barcelona too, and I pretend to know something... sometimes.

Miguel

 

¿Why do my posts show a checkmark on rating? I have not done anything bad !...