Hockeydemon
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Should I save this Ammonium Sulfate?
I made my first batch of red fuming nitric acid today from ammonium nitrate & sulfuric acid. I still haven't gotten the money together for a
stupid fume hood so I just did it in my laundry room with the outside door open.
I reacted 90g of ammonium nitrate with ~40mL sulfuric acid for ~2 hours and got a yield of ~20mL red fuming nitric acid.
I managed to stain my index and thumb finger with nitric acid haha. I did the entire reaction, broke down my apparatus, and cleaned everything with no
problem. Only was it when I went to grab the bottle it was in to label it that I realized the nitric acid had completely eaten away the thread of the
cap and the fumes got my fingers for a second lol.. Lesson learned, thankfully I already had a sodium bicarbonate solution made up for cleaning up
residual acid.
Now then! I stuck all of the ammonium sulfate onto a drying dish, and I was curious so I took a very little bit and put it into a test tube &
added sodium bicarbonate. This is a very vigorous reaction so I was curious what the equation was which it turns out to be
(NH4)2SO4(aq) + Na2CO3(aq) ---> Na2SO4(aq) + CO2(g) + H2O(l) + 2 NH3(aq)
So it makes Sodium Sulfate? Is there any use for this? Or a better use for ammonium sulfate than reacting it with sodium bicarbonate?
Thanks 
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Hockeydemon
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What about making ammonium alum? I know there are easier ways to do this go about this, but would this be possible?
Could I react copper with sulfuric acid & nitric acid to form copper(II) sulfate. Then do a single replacement with copper(II) sulfate &
aluminum to form aluminum sulfate? Then react aluminum sulfate with sodium bicarbonate to form Aluminium hydroxide, which I could then react
that with sulfuric acid, and ammonium sulfate to for ammonium alum? It's a bit intensive for nothing, but if it's possible I'd love to do it .
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woelen
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Your remaining solid is not pure ammonium sulfate. Pure ammonium sulfate does not give a vigorous reaction with NaHCO3, at most some slow bubbling.
Your remaining solid can better be described as impure NH4HSO4, ammonium bisulfate. But it surely also still contains quite some nitrate ions and most
likely it also contains free H2SO4.
It is interesting though to make ammonium sulfate of this. Just add ammonia to this, until the solution is somewhat basic or has a faint smell of
ammonia. Take household ammonia and heat this near boiling and bubble the gas through the solution, until the solution smells of ammonia. Then allow
to evaporate slowly. Crystals of (NH4)2SO4 will form, NH4NO3 is much more soluble and this will remain in solution. Do not simply add household
ammonia to your solid, because of all the impurities in household ammonia. If you want a reasonably pure product, then bubble the ammonia gas through
a solution.
When bubbling ammonia gas through water, beware of suck-back! Use an inverted funnel or an intermediate flask.
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Hockeydemon
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After I bubble ammonia gas through the impure ammonium sulfate will my previously stated way of making ammonium alum be feasible?
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woelen
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Why first use copper? You can dissolve aluminium in dilute sulphuric acid and then add the ammonium sulfate to a solution of aluminium sulfate. In
theory this gives ammonium alum. I think that you will meet many practical problems, but such an exercise indeed can be quite rewarding and you can
learn a lot of it.
[Edited on 26-3-13 by woelen]
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MrHomeScientist
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Would you by chance be the same person I'm talking to on my nitric acid synthesis video?
I was going to make the same recommendation as woelen - it's much simpler to just dissolve aluminum in sulfuric acid directly. To make double salts
you simply need a solution of all the relevant ions, and they crystallize out as solution volume is reduced. See my other video on making alum from a
soda can!
I should probably update my video to reflect woelen's comments on what the byproducts of this reaction actually are. I think it's primarily NH4HSO4,
rather than (NH4)2SO4 as I stated.
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Hockeydemon
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Lol Yeah that would be I, and thank you for the prompt response to your video comment.
So I took a whack at bubbling ammonia through the ammonia bisulfate - I failed.. But I made a video of the horrible apparatus I constructed for it.
You can find that here http://youtu.be/8Z8HaTsk-zk
The setup is crap though so I am going to give it another go, and really simplify it by just boiling ammonia in my Buchner flask through a much
shorter tube attached to a funnel in a beaker of an ammonia bisulfate solution, and then filter out the precipitate.
That being said am I headed in the right direction? Any chance you could tell me what was crystallizing in the ammonia while it was being boiled, it
was only there for about 10 minutes and then it just disappeared. I was using household ammonia, but it did not contain any fragrance or anything..
I forgot to ask.. How do I know when I've bubbled enough ammonia through the solution? You said it should have a faint smell of ammonia, but how would
I know what it smells like while ammonia is bubbling through it? Because you had said that the reaction between ammonium sulfate & sodium
bicarbonate should not be vigorous I tried to use that as a ball park gauge. However after I gave up on my attempt at bubble gas through the solution
I just dumped the ammonia that collected into the intermediate flask (~20mL) into the flask with my ammonium bisulfate with the thought that this
would make the solution basic. But even this did nothing to prevent the reaction with sodium bicarbonate from being extremely vigorous.
What have I failed to understand?
[Edited on 27-3-2013 by Hockeydemon]
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woelen
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You need to bubble a lot of ammonia through your liquid. Also good that you did not add the household ammonia directly. If you have crystals in the
household ammonia, then it must contain a lot of impurities.
As end point you can simply use the smell of ammonia. You should not be afraid to add a lot of ammonia. Excess ammonia is best. The ammonia evaporates
together with water when you crystallize the ammonium sulfate. So, simply bubble ammonia through the liquid and when the liquid has a smell of
ammonia, even when you don't bubble anymore into the liquid, then you have added enough of it.
If you started with 100 grams of H2SO4 or so, then be prepared to use a lot of ammonia. Household ammonia only holds 4 to 5 grams of ammonia per 100
ml and you'll need a few tens of grams, so be prepared to drive off the ammonia of almost a liter of household ammonia.
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