Cryogenic vials...really necessary?

Peter pxpst2 at vms.cis.pitt.delet.edu
Thu Oct 9 11:52:04 EST 1997


In article <61ihrf$rom$1 at infa.central.susx.ac.uk>,
bapn4 at central.susx.ac.uk (Martin Goodson) wrote:

 This ice does not then melt and 
> evaporate because it is so cold. 

I never said the water melts.  I said that it skips the liquid phase and
goes from solid phase to gas phase by a process called SUBLIMATION.  The
gradient that facilitates this is the vapor pressure of the water right
above the frozen sample.


> This as true for the ice in a glycerol
> as it is for the ice sheet in the freezer. There is no reason why water
> would be drawn out of a tube and onto the freezer wall since they are
> both in the same environment (ie very cold).
> 
But they are not the same enviornment.  The coils are colder than the air
in the freezer and thus the moisture gets deposited on them hence the two
enviornments are not equivilant.  The air in the freezer is dryer than the
the air in the tube. And like all reactions they head for equilibrium(Le
Chatelier's princible). Cold air is capable of holding water vapor but not
much.  For a review of the princible look up the definition of relative
Humidity.  Then find out how the relative Humidity is solved for.   

I suggest that you review your general chemistry. 


Peter

-- 
"Don't you eat that yellow snow
    WAtch out where the Huskies go"

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