[steve]

steve asked the Naked Scientists:

Boiling water freezes faster than cold water. Does frozen water boil faster than cold/warm water? If not why not?

What do you think?

[kancha]

Absolutely not. Let us consider certain mass of ice and equal mass of water both at 0 degree Celsius. Now although their temperatures are same, ice has something called Latent Heat of Fusion which is a sort of hidden heat. Now if we were to melt the ice to water at 0 degree Celsius (that is to the same temperature) we would need to give in some heat which is determined by the Latent Heat of Fusion of water and the mass of the ice. So because of this hidden heat, frozen water will need comparatively more heat to boil than warm or cold water (even though they might have the same temperature).

I hope that helps.

[Chemistry4me]

WOW! I never thought of it like that! Good on ya kancha

[lightarrow]

Boiling water freezes faster than cold water.

This is what they teach at school? Will these kinds of internet legends replace real science? Poor us!

Of course, in the right conditions that can happen, but to make a real comparison you should put the hot and the cold water in exactly the same conditions, excepting for their temperature.

What I'm contesting is the fact that looking at the phrase "Boiling water freezes faster than cold water" someone without a proper knowledge could be induced to think it's a kind of law of nature, and, with a large consensus, could also contest a teacher of physics in a school lesson...

Please, let's try not to encourage false science.

[lyner]

The first time I heard that one was in the 1950s. People never learn.