Cryogenic vials...really necessary?
bapn4 at central.susx.ac.uk
Fri Oct 10 05:58:30 EST 1997
Peter (pxpst2 at vms.cis.pitt.delet.edu) wrote:
: 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.
so, ok, I am to believe, from your previous post that
:(air at -20C does not have the capability of holding moisture in a
: liquid state)
and yet also
: Cold air is capable of holding water vapor but not
now could you explain how the direct phase transition from vapour to solid
occurs (sublimation) at atmospheric pressure?
: > 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).
this is true: there will be a slight difference in humidity between the
coils and the tube but i suspect that this will so small to be
insignificant. There will not be much water vapour above ice at -80C.
: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.
is this really necessary?
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