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woelen
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Yes, you can make HNO3 from KNO3 and KHSO4 (or the sodium salts). This is not really easy though, less so than making HCl from NaCl and KHSO4 (or
NaHSO4). This is because HNO3 tends to decompose at the temperatures involved and so there will be a lot of NOx, O2 and H2O as well.
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jimwig
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me thinks a vacuum distillation will result in a high concentraqtion of hno3.
craZy jiM wGGns
--packrat, professional bum. -- once just tired
now REtired.
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hissingnoise
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You could, theoretically, get ~100% HNO3 by vacuum dist..
And from atmospheric dist. ~98%, again theoretically. . .
Is two percentage points worth all that extra trouble?
I wouldn't take everything Fester says in KIE as gospel!
[Edited on 19-1-2009 by hissingnoise]
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vulture
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| Quote: |
With respect, vulture, it's to do with the volatility of the acids, the pot-temperature and the stoichiometry of the reactants, not acid-strength. . .
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With respect, unless otherwise indicated, one assumes conditions are room temperature and 1atm. In that case HSO4- will not protonate NO3- to any
significant extent.
Sand also oxidizes carbon, but only at extremely high temperatures. What I'm saying is that you should give the conditions if they deviate from SOP.
[Edited on 19-1-2009 by vulture]
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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hissingnoise
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Point accepted, vulture. . .my contention was, though, based on the conditions pertaining to the reaction(s) specified in the thread.
In which case, we're both correct!
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Leander
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Yesterday I made some nitric acid with my improvised distillation setup. It involves a glass beaker covered with a thick acid resistant plastic sheet
folded into an upside down cone, and filled with cold water. In the center of the beaker a small glass yar is placed to collect any acid condensing on
the cold sheet. The device is loaded with 150 grams of H2SO4 (96%) and 100 grams of KNO3.
I distilled for 8 hours. First I slowly started heating until about one drop per second came over. Since the colour of the acid was only slightly
yellow I decided to manage that temperature, probably 100-150oC.
The yield was 38,8 ml. The density of the acid was measured using using a pipette and a digital scale with an accuracy of 00.1 gram. The density was
about 1.54 gr/cc, while the maximum density of 100% HNO3 is 1.513. 
I wondered if it's possible that some H2SO4 came over? Has anyone ever had this problem before? I'll check this in a couple of days using some BaCO3.
And how is it even possible that I yielded only slightly yellow acid, while the stuff should have been spewing NOx at that temperatures?
[Edited on 27-2-2009 by Leander]
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hissingnoise
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Better, IMO, to use a proper distillation set-up for HNO3.
If the plastic cone wasn't teflon, or similar, some coating on its surface may have dissolved in, and reacted with your acid---it's also just possible
that H2SO4 splashed into the "distillate".
It would explain the highish density. . .
NO2 in HNO3 also increases the reading and it lightens in colour somwhat as the temperature is reduced.
In any case, acid produced in this way probably shouldn't (for safety reasons) be used to prepare compounds like, say, cyclonite.
You need just an RBF, condenser and receiver---simple and inexpensive.
Eight hours for 39cc. of pretty dodgy HNO3, Jeezzz!
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Leander
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The plastic cone became slightly white after the exposure to nitric acid. No serious decrease in thickness was observed.
Further, I wasn't planning to use this in any RDX synthesis. But why should it be dangerous to do so anyway?
If gives me great satisfaction to design and use improvised apparatus and synthesis. IMO is't not really a challenge, or as much fun to obtain al
sorts of chemicals if I was equiped with a full proffesional lab. Just a matter of interest, has nothing to do with k3wlyness of lack of equipment or
chemicals. 
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Aqua_Fortis_100%
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@hissingnoise , PEAD sheet (Ive used supermarket package) will stand relatively well for some uses before that you need to replace it; and just to be
on safe side, you can use it one time then replace it.. Ive used this method for producing my nitric acid, and is the most inexpensive and OTC that I
came across. All you need for glassware/setup is a ultracheap otc jar , plastic and a moderate heat source..
| Quote: | Originally posted by Leander
If gives me great satisfaction to design and use improvised apparatus and synthesis. IMO is't not really a challenge, or as much fun to obtain al
sorts of chemicals if I was equiped with a full proffesional lab. Just a matter of interest, has nothing to do with k3wlyness of lack of equipment or
chemicals. |
That is also what I always have wondered and what inspire me and is just fun to obtain hard to acquire chemicals through DIY schemes.... Just think
that in a not too much distant future they watch chemical glassware selling.. Then the only way to go is improvise all.. In this case, even
improvising their H2SO4 and nitrate, as some persons want..
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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hissingnoise
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Strong nitric acid with organic contaminants can be dangerously explosive.
An improvised aluminium (not foil) condenser would be safer.
Near ideal would be an aluminium container with a large convex dent on its underside to facilitate dripping.
The big drawback would be the high temperature of the receiver---very inefficient!
Attempted nitrolysis of hexamine using H2SO4 contaminated HNO3 could cause a runaway because hexamine is attacked by H2SO4. . .
IMO, watching HNO3 come over at a rate of several drips ps is fun, too.
With proper distillation, you'll know your acid is pure enough for most porpoises. . .
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chief
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I just wonder, how everyone here takes a lot of trouble distilling the HNO3, still after I posted maybe already 3 times the possibility below, here a
excerpt-copy of my post one page before:
=================================================================
I never did it -- but: Ba(NO3)2 + 2 H2SO4 ==> BaSO4 + 2 HNO3
BaSO4 should ppt., ready ! Has anyone tried this ??
The Ba(NO3)2 might stem from fireworks (those brillant-candles, on the iron-wire):
==> ppt out BaCO3
==> react with some dilute HNO3
==> dry the Ba(NO3)2
==> do the conc. HNO3-reaction, yielding BaSO4
--> recycle the BaSO4, using soda (there was a thread on this, by me)
============================================================
If this works (and I remember to have read about it in some chemistry-book too), then its as simple getting HNO3 + Ba(NO3)2, and letting set. The 100
% HNO3 would be the liquid afterwards, the H2SO4 gone into the unsoluble and heavy BaSO4 (setting fast) ...
Besides: The Ba(NO3)2 does not decompose below 595 Celsius, thats red-glowing. It can therefore be dried efficiently. With the nitrate so dry, and a
dry H2SO4, there seems to be no reason for any much water in the HNO3 later on ... 
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hissingnoise
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| Quote: | Originally posted by Aqua_Fortis_100%
Just think that in a not too much distant future they watch chemical glassware selling. |
Those clouds on the horizon are nearly directly overheard (Bushwhackered?).
Get yer flasks'n'condensers while you still can. . .
Sorry, where was I---oh yeah, I used the field-expedient method, too.
Just once. . .
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Aqua_Fortis_100%
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Yeah, but with nitric made just one time with PEAD I dont think that organic contaminants will be a great issue, and since most(?) of them are
probably oxidized to CO2/H2O, is safe.. Anyway for me at least there is even added safety since I never used that nitric for pyro purposes, just to
make inorganic nitrates that are good to keep around; I would prefer plain H2SO4/KNO3 nitrating system , although it cant be used to nitrate things
like hexamine and can be difficult to others like glycerin.. The major hazard that always worried me are NOx fumes, both in nitric synth and
nitration experiments.. Very nasty thing.. You can detect by smell it in very minute amounts, but like many substances on prolonged exposure you will
be no longer able to detect its acrid smell... They make your lungs go into soup , even weeks after exposure (very acute exposure = immediate
pulmonary edema/death) ; and since your lungs have few nerves you cant feel anything (mild pain in the chest, at most) until its too late.. Actually
NOx fear is the only reason that I have to refuse HNO3 synth with improvised apparatus everytime I can avoid it..
I agree that is very difficult to prepare white nice crystal clear HNO3 free from dissolved NOx only with distillation ; i.e. without urea
nitrate/dried warm air trick .. It was mentioned here, IIRC, that even minute exposure to sunlight will make HNO3 releasing some NOx and therefore
getting yellow tint.. 
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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hissingnoise
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| Quote: | Originally posted by chief
I never did it -- but: Ba(NO3)2 + 2 H2SO4 ==> BaSO4 + 2 HNO3
BaSO4 should ppt., ready ! Has anyone tried this ??
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Chief, if you add dry barium, lead or calcium nitrate to H2SO4 the insoluble sulphate will form on the outside of the granules preventing further
reaction.
Some small amount of HNO3 may form but most will be locked within the grains.
Normally, a saturated stoichiometric solution of the nitrate salt is used, giving dilute HNO3 and the sulphate precipitate.
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Aqua_Fortis_100%
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@ chief
Ba(NO3)2 is somewhat expensive to use in HNO3 manufacturing; I would keep it for green stars... Just use Ca(NO3)2 instead, although very difficult to
dry since it is deliquescent IIRC..
How easily dry Ba(NO3)2 and conc H2SO4 would react to form HNO3? Since BaSO4 is very insoluble, I dont think it be easy to get all Ba(NO3)2
reacting...
But its interesting the possibility that NaOH can digest BaSO4, so can it??? Im not sure if this really works; just a feeling though since BaSO4 is
very stable, insoluble and thus cant be easily decomposed.. I just knew that only way to recover Ba from BaSO4 is through roasting with reducing agent
(charcoal, etc) that can be boring, messy and time consuming or then making a homologue of "incendiary plaster" with BaSO4/aluminium just for eyes
amusement.. Then getting the BaS and dissolving in HCl, avoiding toxic H2S and then converting chloride to nitrate through NH4NO3 (since Ba nitrate
has low solubility on low temp.. Ive made this before) or then making BaCO3 / Ba(OH)2 from aqueous chloride... Overall, messy process.. But its still
an alternative...
EDIT:
| Quote: | Originally posted by hissingnoise
Chief, if you add dry barium, lead or calcium nitrate to H2SO4 the insoluble sulphate will form on the outside of the granules preventing further
reaction.
Some small amount of HNO3 may form but most will be locked within the grains.
Normally, a saturated stoichiometric solution of the nitrate salt is used, giving dilute HNO3 and the sulphate precipitate. |
Oh, sorry.. Ive posted almost the same thing, you beat me first ahaha
[Edited on 28-2-2009 by Aqua_Fortis_100%]
[Edited on 28-2-2009 by Aqua_Fortis_100%]
"The secret of freedom lies in educating people, whereas the secret of tyranny is in keeping them ignorant."
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chief
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The surface-covering would be probably no problem for the following reasons:
==> SO4 is divalent, and tetrahedron
==> NO3 is monovalent and planar
===> give crystal-chemically different structures, probably uncapable of sticking one on the other
Also: H2SO4 (hot & conc.) _dissolves_ BaSO4 to some amount (as literature says), so the mixture of H2SO4/Ba(NO3)2 would only have to be heated, at
most. ..
Also the reaction of BaSO4 with NaOH works in the melt, as equilibrium, but it's easier to boil it for 1 h in conc. soda-solution, thread upon this
here in the forum. I didt it, and it works, is good for making Ba-compounds out of BaSO4, which could be recycled this way.
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hissingnoise
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Chief, you could make a hot saturated solution of Ba(NO3)2 and add to it the calculated amount of 98% H2SO4 with stirring---this will give you dilute
HNO3 + solid BaSO4.
Decanting the solution and concentrating by distillation from its bulk of H2SO4 will give you strong HNO3.
Adding the nitrate to H2SO4 will give a solution of strong HNO3 in H2SO4 with the H2SO4 in excess.
That's how it works. . .
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chief
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Distilling only concentrates up to the azetrope.
But water-free H2SO4 + water-free BaSO4 will give HNO3 + BaSO4 ; since the BaSO4 is so insoluble, it should ppt out, and ready would be the 100 %
HNO3, no water in it (except for small amounts) ; besides it's from a chembook, but forgot where to find the reference ...
Even if the HNO3 would be mixed with excess H2SO4, then this could be distilled much better, since no water in it ... !
I can't believe noone gets the idea ... , and I didn't post it for the first time . Do I miss anything ? I might as well try myself, but I'm not
common to handling such conc. HNO3, also no uses for me of this stuff ... .
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hissingnoise
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| Quote: | Originally posted by chief
I'm not common to handling such conc. HNO3, also no uses for me of this stuff ... . |
sigh! At this point chief, there's little more I can tell you. . .
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chief
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Don't make yourself more important than you are: As you see I avoid it even though I could do it, for the chems I own; eg. the H2SO4 I own since years
(and some nitrates since the 80s, most of them still unused ...), and I just could resist ... ; I'm just not a free-of-will front-pig, like most usual
chemists ...
Also it's not too dangerous, if done with the proper precautions: Little amounts, face- and earprotection, thick unburnable clothing of the right sort
of fibers, that can be removed without pulling it over the head, etc. . I find it lame to play such a hide-and dagger-game: "I can't tell you more at
this point ... " ; anyhow someone probably is gonna try it, and will confirm, some day.
Main thing for me not to do it is: It's not really a thing I'm interested in, besides the theoretical confirmation that it works. So I post it here,
where everyone anyhow is messing around with such things ; the "Im not used to handle conc. HNO3" was just only sort of a warning towards others (it
isn't even really true for me), to check the dangers first, since this is a 1-minute experiment, quickly done without lot's of preparation.
Also it's probably (!) much less dangerous than having the usual conc. H2SO4+nitrate destillation at 150 [Ceslsius], where everyone who ever tried the
effect of H2SO4 alone at this temp would just shy away from it ...
Also: I might do it within a minute, but I definately wouldn't go beyond that point the check if the HNO3 is "really good" or something ..., so it
would be of little value if I did it: I wouldn't check the results ...
[Edited on 1-3-2009 by chief]
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Formatik
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The Ostwald Process
Despite all of the discussion on synthesis here, there has been no lengthy focus or experimentation on one of the most important processes for the
preparation of nitric acid, the Ostwald Process.
I did an experiment some time ago on this where air is mixed with NH3, dried, goes through the catalyst, then into an air-mixer bottle, through water
in a 1L flask, and then into a basic solution (neutralization attempt). The comments are below. A video of the set-up is here. It is a primitive set-up since these were a series of probe attempts.
1. Ammonia. The amount in the small 125mL flask is 15mL of 10% NH4OH. The air stream from the pump goes over the surface of the liquid. The explosible
limits of ammonia in air are between 15 to 30%, a relatively narrow range. Assuming all of the NH3 were vaporized at once its volume would be
something like 2.01mL / 110mL = 1.83%. But since the evaporation is slow, and an air stream is going through it I was working far below those limits.
The receiver water in the 1L flask is about 60mL. With those amounts, maximally 3.55g HNO3 can form from: 3 NO2 + H2O = 2 HNO3 + NO. With more being
possible by further combination of NO. Unwanted side reactions can occur, and these form N2 and H2O. Where sometimes there is also unreduced NH3. I
didn't complete the evaporation, but reckon it takes something like 3 hrs at that amount and rate.
2. Catalyst. For the catalyst a (brass) copper net was burned in free air with a torch, then it was all pressed together. There are better catalysts
to use for this, e.g. as mentioned in Gmelin, Sys. No. 4[N], 665-683. The yield of NO increases with temperature and is dependent on the catalyst
used. According to Gmelin, CuO is a horrible catalyst. Tough luck. Cr2O3 will give a better conversion at a lower temp. (even active at as low as
300º, roasted pyrite also). Pure Fe2O3 will convert 9 to 9.5% pure NH3-air mixtures in good yield, optimal yield is 90% at 670 to 700º. In the
industry, Pt and/or Pt-Rh is used. One could likely take a carrier like pumice, soak in a satd. solution of FeCl3, for some time and then drip in
NH4OH to form Fe(OH)3, and then glow this thoroughly.
3. Drying agent and material. In the bottle above, CaCl2 pellets were used. Other drying agents will work, CaO, Na2SO4, MgSO4, etc. In the industry
liquid ammonia is used, so no need for drying. Since the rubber stopper was attacked (HNO3 will attack rubber, cork, etc), I decided to wrap it in
aluminium foil. It will need to be secured so no gas escapes. I also noticed a significant deformation on the glass tube after hours of heating with
the bunsen burner. So something more thermally stable should be used, e.g. quartz, stoneware, stainless steel, etc.
4. Additional notes. Besides the terrible catalyst choice, air oxidizes NO sluggishly to NO2 (the rate of this conversion increases with colder
temperature), this gets problematic since the stream of air is pushing this gas out. So then the NO escapes and converts to NO2 outside of entire
set-up, reducing yield, posing significant and dangerous health hazard, etc. In the industry, with the mixing process with water an absorption column
is used under pressure, as seen here. What I did do was lead this into a foamy NH3 solution containing a lot of NaHCO3, in hopes to neutralize it. But that didn't work and the
unconverted NO would escape and soon convert to the highly poisonous NO2. Though the gases can easily be lead away using tubes.
Since then I've thought of ways to make this go more smoothly but haven't tried anything. I wonder if conc. H2O2 could be used to oxidize NO
efficiently and more readily: 2 NO + 3 H2O2 = 2 HNO3 + 2 H2O
As well as combining with any NO2:
2 NO2 + H2O2 = 2 HNO3
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kilowatt
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I just rigged up an NO2 producing Jacob's ladder, since I had all the parts around from previous acquisitions. The idea is to run it continuously and
produce some amount of dilute acid over days or weeks of operation, then distill it afterward. It has oiled cooled copper rails (each consisting of a
tube within a larger tube and coaxial flow) and a water cooled glass jacket. Air is fed through the glass vessel with an aquarium air pump and then
bubbled through water to make the acid. The ladder runs on a 7200V 30mA neon sign transformer and has a central Gabriel electrode to improve
starting.
I am having some leakage problems with the oil pump (a hydraulic gear pump which I have coupled to a 19rpm high torque gear motor); the shaft seal is
leaking, and I will need to turn it upside down to lessen the problem. The motor also struggles to push the oil through the narrow circuit, and will
stall unless the oil is warmed up prior to turning it on. A fully integrated, preferably submersible, pump would be preferable but I don't have one.
The NO2 production rate is quite significant; within a minute of running the red color can clearly be seen inside the envelope, and the distinctive
smell can be noticed quite strongly at the outlet tube.
The mind cannot decide the truth; it can only find the truth.
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hissingnoise
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Very nice set-up, kilowatt: I once had something similar and found that cooling wasn't really necessary.
I used aluminium electrodes as I assumed copper would react and the cheap soda-glass jar I used got hot but not too hot to touch.
I used two NSTs in parallel and the vapour in the jar was quite dark in colour.
I figured I needed some kind of packed absorption tower to prevent losses but I never got around to making one.
I did get some very dilute acid but a tower would have made all the difference.
I will try it again now that I've got a good compressor; the original was a fridge-compressor and worked poorly.
A fully maintenance-free Jacob's Ladder would be a continuous source of acid that doesn't use-up H2SO4 for concentration, unlike nitrates. . .
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kilowatt
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Perhaps some air circulation will be sufficient to cool the electrodes? They will definitely need some cooling for continuous duty, in my experience
they get *very* hot. The cooler are they less they will react too, but I have found that copper is not very reactive anyway at least over the time
periods and concentrations I have run this so far.
[Edited on 18-3-2009 by kilowatt]
The mind cannot decide the truth; it can only find the truth.
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watson.fawkes
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I might suggest a pair of tungsten rods for TIG welding for electrodes in such an arc reactor. The ceriated and thoriated versions have lower work
functions, so it's easier to sustain the arc. As a refractory metal, tungsten rods shouldn't need cooling, as long as the contact point of the arc
moves as it should.
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