Here is a web site with lots of useful info on H3PO4:

http://www.innophos.com/brochures/acid/page1.asp

See Table 19 for vapor pressures.

Cheers Willi

Jason Curtis wrote:
> I am looking for some information about how high a vacuum is needed to 
> boil 100% ortho phosphoric acid at room temperature.  I know from my 
> own experience that it does not boil at 90C at 1e-3 mbar but someone 
> asked me it they could increase the vacuum to 1e-6 mbar at room temp 
> and still not have acid moving around.  Thanks in advance for help 
> with this weird question.  If I don't hear anything I guess I will 
> just have to experiment!   Jason
>
> Jason Curtis, Ph.D.
> Stable Isotope Mass Spec Lab manager
> Associate-In Geochemistry
> Department of Geological Sciences
> 241 Williamson Hall
> University of Florida
> Gainesville, FL 32611
> [log in to unmask], office 352-392-2296
> lab 352-392-3344, fax 352-392-9294
>
>

-- 

Dr. Willi A. Brand, Stable Isotope Laboratory      [log in to unmask]
 
Max-Planck-Institute for Biogeochemistry
 
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