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AirCowPeaCock
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Concentration of NH4OH
I'm attempting to concentrate NH4OH from household ammonium by heating the solution to 95 C and bubbling the gas (mostly NH3) through distilled water
in an ice-bath. It works and I get about 20% concentration. The problem is when all is said and done more than half the original volume I put into
the collection flasks (I have them chain linked) is gone. In fact the more volume I use the more % loss. And the flasks further down the line have
more and more water loss--so its not heat dependent.
Advise?
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Hexavalent
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Learn how to spell and then come back to the ammonia.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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neptunium
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he clearly meant ammonia NH3 not a big deal....
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Hexavalent
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Yes, there's that, but there's also the 'advise'. Clearly it should be 'advice'.
Also, I don't think that this is the best route to more concentrated ammonia, as NH3 is still very soluble in water at 95C.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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AirCowPeaCock
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It difficult to get it past 95C, the ammonia solution has a surfactant(?) in it so it boils over even if I put 25 ml in my 250 ml round bottom.
I'm going to toss that though I think. I don't know what I was thinking, not checking the label--obviously I wasn't. I'm also going to scale it up
a bit, move to my 1 L flask, hopefully I can get it to 100 C this time.
..someones a little  <--
[Edited on 1-10-2012 by AirCowPeaCock]
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Hexavalent
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Even at 100C, ammonia is still very soluble in water. Its solubility equilibrium is not like a vast majority of other gasses.
And what did you mean, AirCowPeaCock, by your comment 'I don't think he needs these ideas..literally--obviously he has them all on his own!' on the
thread about t-butyl lithium?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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AirCowPeaCock
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Quote: Originally posted by Hexavalent  | Even at 100C, ammonia is still very soluble in water. Its solubility equilibrium is not like a vast majority of other gasses.
And what did you mean, AirCowPeaCock, by your comment 'I don't think he needs these ideas..literally--obviously he has them all on his own!' on the
thread about t-butyl lithium? |
I mean you don't need to be told what potentially dangerous reagents to "play" with
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AirCowPeaCock
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What about synthesizing ammonium gas through NH4Cl and CaO. My issue is although I have plenty of CaCO3, I don't have a container I can heat it in to
1300 some degrees to decompose it into CaO.
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unionised
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"Even at 100C, ammonia is still very soluble in water. Its solubility equilibrium is not like a vast majority of other gasses."
What would your second guess be?
Oh, BTW, the word is gases, I think that's an example of someone's "law".
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Hexavalent
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No, the word can be spelt either way;
http://www.thefreedictionary.com/gasses
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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neptunium
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how about NaOH? dry with NH4Cl (if you have some)
NH4Cl+NaOH=NaCl+NH3+H2O
it does need to be heated a little but as soon as the mix is completed you'll smell ammonia!
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AirCowPeaCock
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I have plenty of both. Should I bubble it through water, or because of the water content should I just run it through a condenser? Although my
condenser is kinds short, 6 inch liebig. Thank you! How much heat? I think ill add a little water, I don't need 50% solution?
[Edited on 1-10-2012 by AirCowPeaCock]
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Hexavalent
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Why not try both on a small scale, titrate and then compare results? That would be more exciting than just having someone spoon-feed you instructions!
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Pulverulescent
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| Quote: | | Clearly it should be 'advice'. |
Even more clearly, you've been wrongly advised! 
[edit] Because NH<sub>4</sub>OH is less dense than water, and ammonia having high solubility, the 'funnel trick' is required with
circulation (mag stirrer)!
P
[Edited on 10-1-2012 by Pulverulescent]
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AirCowPeaCock
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I would, but I'm low on time..I'm already a few days behind because ammonia hates me! This is part of a school project. Ive decided Ill add enough
water assuming 100% collection to produce 30% w./w. That way even with decreased efficiency it'll produce at-least 20%, which is sufficient--although
not ideal.
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AirCowPeaCock
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Unfortunetly I don't have a mag stirrer, but NH4Cl + NaOH should work just fine, 300 C is easy. Thanks for the help guys!
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Hexavalent
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| Quote: Originally posted by Pulverulescent | | Quote: | | Clearly it should be 'advice'. |
Even more clearly, you've been wrongly advised!
[edit] Because NH<sub>4</sub>OH is less dense than water, and ammonia having high solubility, the 'funnel trick' is required with
circulation (mag stirrer)!
P
[Edited on 10-1-2012 by Pulverulescent] |
I'd have thought when he said 'bubble' he knew to use a funnel . . .I did that once (omitted the funnel) when I was trying to prepare hydrochloric
acid. . .the cold liquid on hot glass broke my reaction vessel!
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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AirCowPeaCock
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| Quote: Originally posted by Hexavalent | | Quote: Originally posted by Pulverulescent | | Quote: | | Clearly it should be 'advice'. |
Even more clearly, you've been wrongly advised!
[edit] Because NH<sub>4</sub>OH is less dense than water, and ammonia having high solubility, the 'funnel trick' is required with
circulation (mag stirrer)!
P
[Edited on 10-1-2012 by Pulverulescent] |
I'd have thought when he said 'bubble' he knew to use a funnel . . .I did that once (omitted the funnel) when I was trying to prepare hydrochloric
acid. . .the cold liquid on hot glass broke my reaction vessel! |
Weren't you using borosilicate?
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Hexavalent
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Yes, but it was very old and probably was damaged inconspicuously.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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AirCowPeaCock
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Must have been...or just some freak occurrence...
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entropy51
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Without looking up the data, I don't think that is
true. If you heat a strong ammonia solution I think most of the NH3 will enter the gas phase before you reach 100 C.
I know for a fact that if you let the water in the absorber vessel become warm (and it does without cooling) that not much ammonia will be absorbed in
the water.
Concentration of ammonia solutions is easier if you start with Janitorial Strength Ammonia from the hardware store. The stuff I get is 15% and
contains no surfactacts.
Edit: According to the Merck Index, water at 15 C holds 38% NH3 and water at 50 C holds only 18%. If you extrapolate up to 100 C you will have very
little NH3 left in solution, a fact that is easily demonstrated if you know how to titrate.
[Edited on 11-1-2012 by entropy51]
Better to remain silent and appear a fool than to open your mouth and remove all doubt.
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AirCowPeaCock
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Thanks entropy51! Im alreading trying the sal ammoniac method..I think it will work looking at it now, but if it doesnt work ill go buy some
janatorial if i can find it!(:
BOLD
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entropy51
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It is possible to concentrate weak NH4OH by distilling something like 1/4 the volume into a chilled receiver which in turn is trapped into a chilled
trap containing some of the stuff you're distilling. I played around with it once, titrating the different solutions, just to see what was possible.
Using the weak household NH4OH I was able to concentrate it by a factor of two to four, according to my notes.
The best method I've found is to make NH3 gas using ammonium sulfate fertilizer and NaOH dissolved in the minimum amount of water and to absorb that
in the janitorial ammonia, chilled quite cold and magnetically stirred so that the less dense concentrated NH4OH doesn't sit on top of the weaker
solution. Once you get the hang of it you can make quite strong NH4OH this way.
Before you buy NH4OH in the store, carefully give the bottle a shake to see if it foams, which indicates the presence of undesirable surfactants.
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AirCowPeaCock
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Thanks for your help, I think this is going to work just fine though. A little NH4Cl impurities, but I can easily remove thoughs through
distilation--the probably wont be of concern for methyl ethyl ketazine synthesis anyways
BOLD
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AirCowPeaCock
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Sorry for the spelling grammer errors. I am in the lab, im trying to type as fast as possible to keep my attention on the reaction. Its going real
slow though, i need a mag stirrer/hot plate!
BOLD
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