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Author: Subject: Dry ice for purifying HNO3 (idea)
kclo4
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[*] posted on 10-8-2005 at 19:26
Dry ice for purifying HNO3 (idea)


:) OK i was thinking (don't know how well but i was) about a way to purify 68% HNO3 that is
does not use H2SO4. now I don't know if CO2 will dissolve in with 68% HNO3 to make H2CO3 but if it can, it would seem to break the azeotrope that HNO3 has with H2O now we all know that when dry ice is added to water it makes a fog of H2CO3 so it seems to sublimate or some how come out, so in theory (if CO2 will dissolve in 68% HNO3) by adding dry ice to HNO3 it would sublimate the carbonic acid thus it would take away the H2O and making purer HNO3 but i don't know if this would work do any of you greater chemist know if it would work?

if it works i don't think it would work as well as H2SO4, but it would make WFNA with out all the work and time it takes for a vacuum distiller and adding urea. to remove the possible H2CO3 left you could just heat it, cool it or just let it sit out for a while for all the CO2 to float away

love to hear any comments about this idea.




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CD-ROM-LAUFWERK
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[*] posted on 11-8-2005 at 10:30


Quote:
but it would make WFNA with out all the work and time it takes for a vacuum distiller and adding urea.

where is the problem?
if u distill only twice, 1. a mixture of 50% HNO3 whit same volum conz. H2SO4 and 2. the destillat + 3/4 volum conz. H2SO4, u already have a HNO3 whit more than 99%!
only a bit NO2, like aplejuice (clear one)
i already can do RDX whit this HNO3 :P
no vacuum, no urea, only a bit water :cool:
i dont think that u real can purify HNO3 whit this method
Quote:

to remove the possible H2CO3 left you could just heat it, cool it or just let it sit out for a while for all the CO2 to float away

and what leaves if the CO2 comes out?
right, H2O, so nothing changed...
also CO2 only gives a bit H2CO3 in solution...
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kclo4
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[*] posted on 11-8-2005 at 10:55


" And what leaves if the CO2 comes out?
right, H2O, so nothing changed...
Also CO2 only gives a bit H2CO3 in solution... "

i was referring to the small amount that was left in the HNO3

"where is the problem?
If u distill only twice, 1. A mixture of 50% HNO3 whit same volume conz. H2SO4 and 2. the distillate + 3/4 volume conz. H2SO4, u already have a HNO3 whit more than 99%!"

i am just trying to find other ways to make WFNA plus this would seem to do drop in some dry ice and wait

also there must be a maximum percent that H2CO3 can have in a solution and that would be why the white fog comes off it makes little H2O droplets from the decomposition of the H2CO3

I would think that's you would want to cool the HNO3 then add dry ice so the H2CO3 does not decompose as fast thus giving it time to leave the solution or after words you might want to heat it so the H2CO3 come off

see if the CO2 floats away the H2O will want to come with in theory but it would only come off until it reached a certain percentage of HNO3

thank you for your post




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12AX7
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[*] posted on 11-8-2005 at 12:05


The mist is from supercooled water vapor, and it isn't an efficient process. It depends on water vapor evaporating quickly, to be supercooled by the CO2(s) and form a cloud, so works best with rapidly evaporating water i.e. hot. It has nothing to do with H2CO3 that I am aware of.

What a weak acid will ever do with a strong oxidizing acid like nitric is beyond me!

Tim




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[*] posted on 13-8-2005 at 06:32


"now we all know that when dry ice is added to water it makes a fog of H2CO3 "
Nope, it doesn't.
H2CO3 is quite difficult to make.
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BromicAcid
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[*] posted on 13-8-2005 at 07:40


I could see this working, the process similar to sparging where one bubbles dry air through a aqueous solution to increase the concentration of one of its constituents. However there is also the cold temperatures to consider here as well as the fact that it is CO<sub>2</sub> bubbling through it (which I don't think would make much of a difference). But this is just speculation, it could just as easily not work or increase the concentration only a few precent. Sounds like an easy experiment to do providing one has access to dry ice and some titraition equiptment to test the results.

Edit: Speaking of sparging this could work well for increasing the concentration of H<sub>2</sub>O<sub>2</sub>.

[Edited on 8/13/2005 by BromicAcid]




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Lambda
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[*] posted on 13-8-2005 at 09:16


Freeze cooling also works fine for Ethanol / Water sepperation. Not very efficient though, but worth mentioning. This procedure certainly has it's benefits, especially when dealing with thermically unstable compounds. I like BromicAcids proposal for H2O2 concentration enhancement idea. It certainly looks feasible.

Is every thing OK with you BromicAcid, after that chemical plant disaster ? I hope there were no casualties.

[Edited on 13-8-2005 by Lambda]
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