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guy
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Making own Nitric Acid
can u make nitric acid out of ammonia w/ out platinum catalyst?
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darkflame89
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Maybe, but industrially, ammonia is oxidised at high temp. of 500 degrees celcius, and at pressures of 250 atm, using the catalyst. Nitrogen monoxide
is produced which is subsequently furthur oxidised to form NO2, which can then be dissolved in water to get HNO3
Ignis ubique latet, naturam amplectitur omnem.
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Marvin
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Are you sure you arnt confusing that with the Haber-Bosche process for producing ammonia darkflame?
It can be done without platinum, Iron oxide works, though somewhat less well. Its a difficult process to get working on a small scale, and
Megalomania on roguesci has failed to make it work.
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hodges
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http://mattson.creighton.edu/NH3/
Demonstrates making NO2 using NH3 and oxygen at normal atmospheric pressure with a copper catalyst.
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darkflame89
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Amazing I can start making nitric acid at home now. If i largescale the process
stated at the website, am i going to get any appreciable amounts??
Ignis ubique latet, naturam amplectitur omnem.
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hodges
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Presumably you can. It will be impure though - at the very least it will contain NH4NO3 since not all of the ammonia will react.
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darkflame89
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I can always distil the solution right?? Or i can add sulphuric acid in to react with the ammonium nitrate and distill the volatile, nitric acid.
Ignis ubique latet, naturam amplectitur omnem.
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hodges
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Sure. I thought, though, that since you were trying to make nitric acid this way you didn't have access to other acids or a distiller. If you
have sulphuric and a distiller why not just use the ammonium nitrate from a cold pack or fertilizer?
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darkflame89
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True, true, it is just that while i can improvise a distiller, i definitely do not have sulphuric acid. The strongest acid i can find is phosphuric
acid, sold as some kind of anti rust.
This setup has jus a teenny problem, it is quite unable to produce continuous supply of nitric acid; i have to keep taking the coiled copper wire out
and heat it on the fire. Anyway to remedy this??
Ignis ubique latet, naturam amplectitur omnem.
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unionised
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Have a look at this thread
http://www.sciencemadness.org/talk/viewthread.php?tid=1673&a...
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The_Davster
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Darkflame89: You could electroplate some copper onto nichrome wire, and then just use electricty to keep it hot. Or run the ammonia and oxygen
through a copper pipe filled with fine copper wire or copper wool and then just heat the pipe.
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darkflame89
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Good idea that one, i will scoot around to find nichrome wire.
Ignis ubique latet, naturam amplectitur omnem.
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axehandle
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Good idea that one, i will scoot around to find nichrome wire
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McGyverize a broken hair drier. It should contain a fair length of coiled NiCr wire.
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
\"Verbing nouns weirds the language!\"
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darkflame89
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Upon closer thought, how does Cu catalyse the reaction of ammonia and oxygen to nitrogen monoxide. For starters it might start like:
2Cu + O2 --> 2CuO
Then NH3 + CuO --> ??
Ignis ubique latet, naturam amplectitur omnem.
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darkflame89
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Hmm, encountered this website a while ago, it more detailed and have videos.
The reaction is exothermic and keeps the copper wire hot for a long time.
Ignis ubique latet, naturam amplectitur omnem.
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Theoretic
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If you have AN and a distilling setup, but no acid, use a pinch of salt as a catalyst:
5NH4NO3 => 9H2O + 2HNO3 + 4N2
 
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Marvin
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On strongly heating ammonium nitrate contaminated with transition metal salts, particually copper there is a large risk of a detonation.
I'm unsure what you meant by 'salt', but I'll assume a copper salt.
Normally it produces N2O of course and any catalyst would have to accelerate one reaction and not the other. Only tiny amounts of acid are produced
without a catalyst.
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neutrino
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I think he meant NaCl salt. I remember seeing refernces to a reaction like this on the forum. It is catalysed by chloride ions.
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Magpie
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68% nitric acid
I would like to make the subject acid using sulfuric acid and potassium nitrate.
I have searched and not found a recipe that looked authoritative (or even compeletely believable). However, I have found believable tidbits and have
assembled them into my own recipe. I would like to list the parameters for review of the forum, as this exercise has the potential to turn nasty.
Here are my operating assumptions, assuming the following reaction is predominant:
H2SO4 + KNO3 -> HNO3 + KHSO4
1) perform in hood using borosilicate glass vessels
2) use heating mantle, 500 mL RBF, Claisen head, cold water cooled condenser, vacuum adapter, and RBF receiver in ice bath, thermometer at still head;
all ground glass fittings wiped free of grease
3) use vacuum distillation at 30 mmHG absolute pressure; estimated boiling temp of azeotrope is 60 deg C
4) use ebulliator to prevent bumping
5) use isolation trap in vacuum line to aspirator
6) use mole ratio of H2SO4/KNO3 =0.674
7) add enough water to give azeotropic 68% HNO3
8) take it slow and use 100 mL H2SO4, at least for the 1st batch
I would appreciate any comments, suggestions, or questions. If all looks good I will perform this preparation and post results with pictures.
The single most important condition for a successful synthesis is good mixing - Nicodem
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The_Davster
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I would use slightly diluted sulfuric and directly distilling off the azeotropic acid, instead of diluting the fuming nitric after, just for a bit
extra margin of safety. After all why mess with the ~98% stuff when you only want ~70%. Also, adding water to your 98% nitric would be very
exothermic.
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ordenblitz
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Magpie,
IMHO making HNO3 using sulfuric acid and potassium nitrate is not as difficult or dangerous as you have imagined. I have done it several dozen times,
in as many years without incident.
Typically I use a 2000ml flask as the yields from a 500 ml sized batch are fairly small, at least for my effort.
Use a slight excess of H2SO4 as it makes the removal of the sulfate remains from the flask easier. Also when cooling after the distillation, just
before the sulfate starts to solidify, carefully add some water from a wash bottle. This keeps a solid concrete mass from forming. If you have a
silicone heat mitt, you can pour it out while it is still liquid.
In my experience an ebulliator is not necessary as the distillation is very smooth and tame.
Ice chilling the receiver flask is not necessary if you move a reasonable amount of water through the condenser.
Also, while I have done it under reduced pressure, it really isn't worth the time and effort.
Personally I would use the 98% H2SO4 if you have it, and make the concentrated HNO3. Save some of that and dilute if you need it of lower
concentration. Dilution of conc. nitric is a non issue compared to H2SO4.
After you do this for the first time, you will wonder what you were worried about in the first place.
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garage chemist
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Using vacuum creates more problems as it solves if you want to make only 68% HNO3.
With vacuum, the boiling point of the acid will be something like 30°C (if you use dilute H2SO4 to directly distill the 68% acid- if using conc.
H2SO4 the bp will be even lower). This calls for highly effective cooling and immersion of the receiver in ice.
Don't use vacuum! Vacuum is only recommended if you want to make white fuming 99% HNO3, i.e. the kind necessary for RDX or PETN.
Distilling HNO3 from KNO3 and H2SO4 is a piece of cake if you have an all- glass distillation setup. Distill at ambient pressure and use dilute H2SO4
which directly gives 68% HNO3.
Let the KNO3/H2SO4 mix stand for about an hour before distilling for the reaction to take place.
Of course you can also distill fuming acid from conc. H2SO4 and KNO3 at ambient pressure, but it will be only of about 90% concentration and of yellow
color, due to slight decomposition. But on diluting to 68% this becomes colorless, because at this concentration the dissolved NOx react with the
water to form more HNO3.
The 68% acid, no matter if directly distilled or made by diluting fuming acid, should be redistilled and the boiling curve be observed. This is the
best method to find out the actual concentration. 68% HNO3 boils constantly at 122°C.
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neutrino
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I can't remember who it was, but someone here talked about distilling at atmospheric pressure vs vacuum. Their conclusion was that a vacuum
distillation was no better for decomposition that atmospheric distillation and that most of the decomposition that occurred could be blamed on
sunlight.
I can't remember any specifics or which post it was. Maybe someone here remembers, I'm too busy to find it right now.
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Magpie
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Thanks very much for these valuable comments. Most of all thanks for talking me out of using vacuum. I was getting concerned over what HNO3 vapors
were going to do to my CPVC and rubber hose vacuum line.
The single most important condition for a successful synthesis is good mixing - Nicodem
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ordenblitz
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Garage Chemist said:
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Let the KNO3/H2SO4 mix stand for about an hour before distilling for the reaction to take place.
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Actually, the displacement reaction starts immediately forming HNO3. No need to wait at all.
In fact, things will happen real fast when using 98% H2SO4. You should probably use a 2 neck flask with an addition funnel for adding the acid because
if you use a single neck, you probably won't have enough time to assemble your adapter and condenser before nitric vapors starts coming over.
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