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Author: Subject: NH3-water azeotrope?
BASF
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[*] posted on 29-11-2005 at 07:44
NH3-water azeotrope?


I am desperately looking for evidence if there is an azeotrope of NH3-water.
I did some extensive searches on google, but it did not return anything sofar.


Please help!

[Edited on 29-11-2005 by BASF]
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[*] posted on 29-11-2005 at 08:18


LeChatelier tells me that gaseous ammonia should be released when you boil ammonia water.

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[*] posted on 29-11-2005 at 08:54
Ammonia


Boiling NH4OH releases the ammonia from the water. CRC 62nd Edition(1981-1982) states
that NH4OH exists in solution only - the same as potassium and sodium hypochlorites.




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[*] posted on 29-11-2005 at 09:12


I read elsewhere that in very dilute NH3*H2O-solutions the increased degree of ionization leads to formation of an azeotrope....only, there is very few info about azeotropes! - I need the info for a work about vaporizable heat-transfer-media.
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[*] posted on 29-11-2005 at 11:44


"LeChatelier tells me that gaseous ammonia should be released when you boil ammonia water. "
What does he tell you about boiling a mixture of alcohol and water?

Is there any evidence for NH4OH as a covalently bound compound, or even a stable ion-pair in water? Does it actually exist?
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[*] posted on 29-11-2005 at 21:45


I looked in my Perry's and CRC handbooks (circa 1965) at the list of azeotropes. The water-NH3 system was absent.

I also have a liquid-vapor equilibrium curve for this system in one of my old textbooks (at 100 atm). It showed absolutely no tendency for the formation of an azeotrope. All gas mixtures were much richer in NH3 no matter the concentration in the liquid.

[Edited on 30-11-2005 by Magpie]




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BASF
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thumbup.gif posted on 30-11-2005 at 04:24


Thanks a lot, Magpie!
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[*] posted on 30-11-2005 at 06:17


Quote:
Originally posted by MadHatter
Boiling NH4OH releases the ammonia from the water. CRC 62nd Edition(1981-1982) states
that NH4OH exists in solution only - the same as potassium and sodium hypochlorites.
Sorry, this is a little off topic but couldn't you technically just let a solution of hypochlorite evaporate at room temperature (granted this would take a long time).?



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Darkblade48
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[*] posted on 30-11-2005 at 08:35


Quote:
Originally posted by Douchermann
Sorry, this is a little off topic but couldn't you technically just let a solution of hypochlorite evaporate at room temperature (granted this would take a long time).?


If you let a solution of sodium hypochlorite evaporate, you'll eventually be left with sodium chloride.
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[*] posted on 2-12-2005 at 12:15


Darn. Well thanks for the information.

[Edited on 2-12-2005 by Douchermann]




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[*] posted on 2-12-2005 at 12:39


I seem to remember reading somewhere that while difficult, non-aqueous NaOCl is possible. May have involved elevated (but not high) temperatures under vacuum, but I can't recall. Though I am sure I have read of this being possible.
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[*] posted on 2-12-2005 at 17:15


If there were a salt of sodium that melted at a low enough temperature that the hypochlorite won't decompose appreciably, you could fuse with chlorinated lime. Or...hell...can you just chlorinate powdered lye?

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[*] posted on 2-12-2005 at 17:20


Id imagine youd have to dissolve the lye in water, so Cl2 would form HCl + HOCl . But i could be wrong.
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[*] posted on 2-12-2005 at 18:55


Quote:
Originally posted by stygian
Id imagine youd have to dissolve the lye in water, so Cl2 would form HCl + HOCl . But i could be wrong.

Adding Cl2 to NaOH results in the following:

2NaOH + Cl2 --> NaOCl + NaCl + H2O

Of course, you have to carry out the reaction at low temperatures to prevent the NaOCl from decomposing
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[*] posted on 2-12-2005 at 18:56


very low temps, considering NaOH + H2O => heat

or would the amount of heat be negligible?

[Edited on 3-12-2005 by stygian]
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[*] posted on 2-12-2005 at 20:58


Once the NaOH is in solution it will not continue to evolve heat. You just simply let the solution cool down to room temperature and then add the chlorine.



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[*] posted on 2-12-2005 at 21:24


Edit: blah. nevermind

[Edited on 3-12-2005 by stygian]
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