Akira990
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How to prepare ammonia solution ?
First i want to say i need ammonia to make hexamine, i have 36% formaldehyde solution...
I already prepared ammonia gas (sodium hydroxide + ammonium nitrate) so i have some experience with that.
Problem is, in this case, when i bubble ammonia gas through water how i can determine % of ammonia in water.. ?
I give some thought to this problem and i think i should go for maximum solubility on 25C, thats 31% but again i have some problem. How i can know
when i reach that point (maybe measuring weight of solution) so i do not spend much material on making ammonia for nothing..
I hope you can understand what i wrote here cause my english is not very good..
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aga
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NH3 is more soluble at 0 C.
Run some ammonia, then titrate the solution to find current concentration.
If too low, run some more gas in.
Repeat until at required concetration.
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WGTR
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I think you answered your own question. Weighing it is probably the easiest way, if you have a good scale. As aga says, cool down
the receiving flask. Also, consider that the solution will "grow" in volume as ammonia gas is passed into it, so don't start with too much water.
Trying to saturate the solution with ammonia at a given temperature can be wasteful of ammonia. At close to equilibrium the excess ammonia escapes.
It's more efficient to cool the solution down and add ammonia until the desired concentration is reached. Also, as you may know, water heats up as
ammonia is added, so active cooling should be used.
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Akira990
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Thx for helpful answers.. I know at close to equilibrium the excess ammonia will escape but i wont try to smell it to confirm that 
I know solution will heat up as ammonia is added, i stated in my first post i had experience with ammonia gas. I bubbled ammonia gas through 80%
acetic acid to make ammonium acetate (pain in the ass to get rid of the little water)
I also done some research before posting here and i know about titrating technic aga mentioned but i am not familiar with it so if you can give some
link where i can learn it would be rly helpful..
I have good scale so that is not problem...
I think i will measure weight of distilled water before bubbling ammonia through water and after i am done so i will calculate how much ammonia i have
traped in water...
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Justin Blaise
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Here are some links to procedures for titration of ammonia.
http://www.meduniv.lviv.ua/files/kafedry/tokshim/English/Ana...
https://www.dlsweb.rmit.edu.au/toolbox/Laboratory/laboratory...
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hissingnoise
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| Quote: | | Problem is, in this case, when i bubble ammonia gas through water how i can determine % of ammonia in water.. ? |
The high solubility of ammonia requires the inverted funnel approach and the soln needs continuous stirring to cope with the lower density (0.880) of
NH4OH!
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blogfast25
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| Quote: |
The high solubility of ammonia requires the inverted funnel approach and the soln needs continuous stirring to cope with the lower density (0.880) of
NH4OH!
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I've lead the NH3 straight into the water without problems, no inverted funnel. It's on this site somewhere. If the flow of NH3 is high, the inverted
funnel method might not work so well, see also Magpie's recent problems with HCl absorption from an FC reaction.
[Edited on 17-11-2014 by blogfast25]
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hissingnoise
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| Quote: | | If the flow of NH3 is high, the inverted funnel method might not work so well. |
I found that using a funnel with high flow rate loses NH3 from the funnel as the lighter hydroxide sits at the surface preventing further
absorption.
But with vigorous stirring, absorption proceeds smoothly until saturation is reached!
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