Posted by Natalie L. Smith on Apr 18, 2002 at 11:37
Re: Question Re: Boiling Water in Microwave Oven (Kasasafras)
Bobbapink's site gives a nice explanation. Here is a cool related phenomenon to try:
Superheating occurs when the water is ABOVE the boiling point, but is in a hyperstable situation where there is no nucleation ("seeding") sites for the growth of bubbles. Once you have even a very small bubble formed, it is very easy for the high energy water molecules to add on to it and go into gas phase.
The same is true for freezing. It is possible, sometimes, for something to go below its freezing point but stay in liquid form if there are no good sites for those first few molecules to bond together into the start of a crystal. Then, a sudden shock can instigate very sudden, rapid crystal formation.
TRY THIS!: Buy a box of those freezer pops - - the kind in the long plastic baggie things. ("Kool-pops"?) Put a bunch of them in your freezer and come back in a few hours. By that time, they should have had ample time to reach a temperature below their freezing point, but, very often you will find that some are not frozen. Take out one of the non-frozen pops and slap it down - hard - on your kitchen counter. Now, watch. It will freeze before your very eyes. You can watch the crystal grow across the length of the pop. Fun!
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