Re: [Phys-l] sudden Vacuum freezing

[John Mallinckrodt <ajm@csupomona.edu>]

On May 7, 2007, at 5:03 PM, Michael Edmiston wrote:

> John M's movie is great, but I'm having difficulty believing it is  
> solid
> ice.  As John D. said, some water must remain.  In fact, in a typical
> freezer in which the temperature is 0F (-18C) I think rough  
> calculation
> would indicate only 25% of the water would freeze.  So I wonder if  
> what we
> see in John M's freezing bottle is the propagation of a slush that  
> is 25%
> ice and 75% water.
>
> John (M), have you ever removed the cap and pushed a rod or knife or
> something into the bottle to find the consistency of the ice/water/ 
> whatever?

Several of my colleagues have reproduced the experiment, including  
one who managed to pour the water into a measuring cup and back into  
the bottle before it froze, but I haven't done so myself.  We also  
considered the latent heat and concluded on that basis that the  
product couldn't be solid ice.  Indeed, the opacity of the product in  
the video makes it pretty clear that it isn't.

I've been more interested in the question of how one might get a  
handle on the speed of propagation of the phase change front.

John Mallinckrodt

Professor of Physics, Cal Poly Pomona
<http://www.csupomona.edu/~ajm>

and

Lead Guitarist, Out-Laws of Physics
<http://outlawsofphysics.com>