Allen wrote:

> ...The gas law formula is PV=nRT  so V (volume) = n (avogadro's
> > number, 6.02 x 10 to the 23) x R (molecular weight, or weight of one >
> mole ...
>

You could have quoted the corrected formula (I did post it below my first
attempt, above)   :)

> In the process of reaching sublimation temperature for the OA, the OA and
the water of hydration part their ways, or do they?  Has anyone really
analyzed what happens?  Do they recombine immediately on re-solidification
or before?

Perhaps they do not recombine.  Oxalic acid has the dihydrate form, which
is a crystal, and it also has an anhydrous form which is a powder.  It may
sublimate as the anhydrous form.   Many crystals do.  So, for example,
bluestone or copper sulphate pentahydrate when it is heated (not to
vaporization, but just heated) drives off the water and becomes anhydrous
copper sulphate.  The pentahydrate form is a bright blue crystal.  The
anhydrous is a dull blue powder.  I used to grow copper sulphate crystals
when I was a kid.  You had to protect them from drying out.

It also may be that the anhydrous oxalic acid is easier to make a fine
powder of than the dihydrate for the use you are speculating about.  Just
more speculation on my part.

Stan

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