My Mates yesterday said that if you put hot water in a cube tray to freeze it takes a shorter time to freeze than cold water does. Firstly is this true and secondly how?
search for "Mpemba effect".
Apparently it is true sometimes.
There are a few hypotheses listed on wikipedia...
and a few links for you to find your answer.
This was on Brainiacs the other week. Boiled water takes a lot quicker than tap water to freeze because its been purified. Where as tap water has isnt properly purified. Hope this helps u me and my hubby tried this out as well as we didnt believe it either. But according to Brainiacs its true anyway!
I posted this and it was removed. I can only assume someone messed up as I can't think of any reason why anyone would object to it:
I'll leave the why to other people, but in laboratory conditions and beginning with large quantities of very hot water and precision-controlled freezers, hot water does freeze faster than cold. In your ice cube tray at home, you won't notice much if any difference.