Originally posted by Uncle Al:
Phase transition requires a nucleation center to reduce activation energy and trigger kinetics. Clean liquids in smooth containers (especially viscous liquids) supercool. Ditto for liquids superheating. Melting starts at crystal imperfections that are always abundant.
PET containers are extremely smooth on the inside. Water within is typically filtered to remove particulates. There are no flaws to allow nucleation and trigger crystallization until you shock the supercooled fluid. Filtered distilled water pressed between two clean microscope slides can be cooled as low as -40 degrees and remain liquid.
Water microwaved a very smooth ceramic cup works similarly. You take it hot out of the microwave, add a teabag, and it explodes in your face.
That's it Al! This is by far the most logical response. Thanks, this makes perfect since to me.
