Concentrating Nitric Acid - Archive File

[megalomania]

Demolition
Frequent Poster
Posts: 158
From: Australia
Registered: FEB 2001
posted 02-15-2001 01:17 AM
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I recently brought 2.5 litres of 70% Nitric Acid for $20 bucks.I am hoping to make RDX but as the concentration is not high enough I can not.I've read that by adding concentrated Sulfuric Acid to the Nitric Acid it will distill the Nitric Acid and leave a concentration of about 95% to 99%.Is this correct and would it be sucificent enough to make R.D.X.All help would be greatly appreciated.
Demolition



wantsomfet
Frequent Poster
Posts: 236
From: EU
Registered: JAN 2001
posted 02-15-2001 06:02 AM
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If you have proper destillation eqipment, it's no big thing, just distill the HNO3 under vacuum.
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for best catfood visit:
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Demolition
Frequent Poster
Posts: 158
From: Australia
Registered: FEB 2001
posted 03-08-2001 06:12 AM
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quote:
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To concentrate nitric acid you mix it with twice it's volume of concentrated sulfuric acid in a distilling flask. Distill it at as low a temperature as possible. You may have to do this twice to get very highly concentrated nitric.
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So does this mean if I want to concentrate 100ml's of 70% Nitric Acid I add 200ml's of concentrated Sulfuric acid and then distill.
Could it distilled without a vacuum source?
Would it be sufficient enough to make RDX?
All help is greatly appreciated
Demolition



ezekiel
Frequent Poster
Posts: 110
From:
Registered: SEP 2000
posted 03-08-2001 03:14 PM
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no.
not strong enough.
you need pure (that's 100%) nitric acid with minimum impurities for a decent yield.
You may get no yield.
And as for that distillation shit,
you need a vacuum pump (expensive) and jointed glassware (even more expensive) but if anybody wants to borrow mine then come over.
Adding sulphuric acid is a bummer unless you have a pump - coz when you try to distill the acid out it will decompose.
you wil get a product, but it will be impure (NO2, NO, N2O etc etc).

If you do not have pure acid the reaction will often not happen.
i think about 90% acid by weight (I forget the mass...) is about sufficient if you can't get anthing else.
Oh and BTW red nitric acid is not suitable as you will produce instable shit that is crue and useless.


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Ezekiel

'Things bad begun make strong themselves by ill'



blackadder
Frequent Poster
Posts: 313
From: London
Registered: DEC 2000
posted 03-08-2001 04:03 PM
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Add KNO3 to some 90-99% H2SO4. This way you will obtain 100% pure fuming HNO3.
Look in KIPE for it, read the "RDX manufacturing" section, it has the instructions there.



ALENGOSVIG1
Moderator
Posts: 766
From: Vancouver, Canada
Registered: NOV 2000
posted 03-08-2001 08:16 PM
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You will not get high purity Nitric from kno3 + h2so4 easily.Y ou'll only get high purity acid if you do not overheat, which is actually quite difficult. If it starts to boil, water will evapourate and condense in the colling coil. You are then left with low purity acid. Once it starts to boil it will actaully take about 1 min to stop. you must also start off using extrememly pure h2s04. BTW, technically, there is no such thing as 100% nitric acid.
[This message has been edited by ALENGOSVIG1 (edited March 08, 2001).]



Cricket
Frequent Poster
Posts: 160
From: USA
Registered: OCT 2000
posted 03-08-2001 09:24 PM
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I don't got much time so I can't go in depth. Somewhere, sometime, in a land far, far away, Megalomania had a topic about how it is possible to make up to 120% (I believe) nitric acid. Just do a search, it should show up even though I haven't saw it in a long time. It does require some equipment.


ALENGOSVIG1
Moderator
Posts: 766
From: Vancouver, Canada
Registered: NOV 2000
posted 03-08-2001 10:03 PM
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Interesting. i always though that the nitric absorbs water.


Jumala
Frequent Poster
Posts: 200
From: Germany
Registered: OCT 2000
posted 03-08-2001 10:23 PM
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Hallo Demolition,
at first, nitric acid with more than 98-99% is impossible and any stuff cannot have more than 100%. I´m not a chemist but nitric acid needs a little bit of water to be a liquit acid.
(For example: The max. concentration of HCL is 38%)
I think it will be more complicated to concentrate 70% acid up than making new acid from H2SO4 and nitrate.

In my book (Scheidt/Flörke 1942)nitric acid is made without vacuum. It works with a good yield of fuming acid. You need glassware with NS 29 plugs (erlenmeyer flask, liebig cooler). Rubber, PVC or cork isn´t acid resistent.
Perhaps you can concentrate your acid up with the same method by destilling H2SO4 + nitrate and put the arising NO2 into the weak acid.




ezekiel
Frequent Poster
Posts: 110
From:
Registered: SEP 2000
posted 03-09-2001 11:48 AM
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Ah, so many interesting references!


I'm afraid to say that you can get 100% nitric acid.
Just in the same way that you can get 100% water.
Or salt.
Or wood.
just becasue you have enver ahd it does not mean it does not exist.
Then again, you could be right and hundreds fo years of chemistry and physics is suddenly falsified!


Of course you can get nitric acid from a nitrate salt and sulphuric acid. But it is not pure, not even remotely.


Pure nitric acid, for those still unconvimced, is a steaming liquid. Hence the term "fuming acid". The acid fumes when there are not enough water molecules to dissolve the gas. Thus some is released. 100% acid will fume alot, as there is not water.


when megalomania spoke of "120% nitric acid"; what he actually said was 120% sulphuric acid.
Sorry guys.
And even then it was only a metaphor. He said it was 120% becasue it was a chemical that could produce 1.2 times of sulphuric acid.
The chemical was oleum I believe. It is essentailly pure (that's 100%) sulphuric acid with alot of sulphur trioxide dissolved in it.


And, finally yes you ca nget over 100% of something. Didn't you ever do GCSE level maths?
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Ezekiel

'Things bad begun make strong themselves by ill'



no_name_available
New Member
Posts: 25
From: germany (?)
Registered: JAN 2001
posted 03-12-2001 04:38 PM
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hi,
if i want to synthesise HNO3 by distilling H2SO4 with NO3-salt, which of the following reactions will happen ? i am sure #2) will do it but i also read #3) somewhere - which is comparable to #1) - which wont work.

1) 1 H2SO4 + 2 KNO3 -> 1 K2SO4 + 2 HNO3

2) 1 H2SO4 + 1 KNO3 -> 1 KHSO4 + 1 HNO3

3) 1 H2SO4 + 2 NH4NO3 -> 1 (NH4)2SO4 + 2 HNO3

4) 1 H2SO4 + 1 NH4NO3 -> 1 NH4HSO4 + 1 HNO3

Thanks for all replies.



HMTD Factory
Frequent Poster
Posts: 225
From:
Registered: FEB 2001
posted 03-12-2001 08:50 PM
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In previous context, ammonium cation will behave like potassium cation. In fact, in most cases an ammonium ion emulates a potassium ion.
They all can happen depend on quantity of H2SO4.



Mr Cool
Frequent Poster
Posts: 991
From: None of your bloody business!
Registered: DEC 2000
posted 03-13-2001 12:56 PM
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When he said 120% acid, I thought he meant HNO3 with a load of NO2 dissolved in it, kinda like the HNO3 equivalent of oleum.


Dhzugasvili
Frequent Poster
Posts: 64
From:
Registered: APR 2001
posted 05-12-2001 09:46 AM
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This is what I did: I bubbled NO2 through 70% nitric acid. I managed to get the nitric in the decomposition vessel to decompose by adding formaldehyde, 40%. the receiving vessel was in an ice bath and tubing was glass. Formaldehyde was added rapidly sometimes and nitric fumed NO2 in excess. The product in the receiving vessel was a deep green colored nitric acid, why the fuck is it green? Is it supposed to be, heck, it fumes alright!


Kroways
New Member
Posts: 19
From: Czech Republic
Registered: APR 2001
posted 05-12-2001 06:59 PM
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ezekiel wrote:
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I'm afraid to say that you can get 100% nitric acid.
Just in the same way that you can get 100% water.
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I'm afraid you are wrong. There is something which they call dynamic equilibrium in the fuming nitric acid. This equilibrium apply to HNO3 and all types of nitroxen oxide and its di/oligo/mers. It is dynamic because the composition of the acid is not constant. It depends on current temperature, pressure, presence of light etc.. This causes the colour changes, which accompany temperature changes etc. There will always be a small amount of substances other than HNO3. The only form of absolutely pure HNO3 is(in my opinion) an ideal crystal at the temperature 0 K(-273.15°C)
On the other hand 100% pure water is quite normal. It will never be 100% practically, but number of 9's(99,99...) can be high even at the room temperature. You just redistill it so many times in absolutely pure tin apparatus that almost nothing is dissolved in the final product. The conductivity of pure water is VERY low, because only a small number of ions exist there. For example it is VERY difficult to obtain pure water with pH 7 by normal distillation. pH of normal distilled water which you buy at the gas pump is ~5-6, because of CO2 dissolved in it.

So this is for you to better understand HNO3. It is a kind of substance, which is not as stable as others. This is the fact, which is to be counted in.


ezekiel wrote:
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The chemical was oleum I believe. It is essentailly pure (that's 100%) sulphuric acid with alot of sulphur trioxide dissolved in it.
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Another nice example of dynamic system. Have you ever seen oleum? They told us it is SO3 dissolved in H2SO4 at the elementary school The reality is different... you can find several different types of molecules, which co-exist here(SO3, H2S2O7 .. i don't know them all, but can look in some wise book). Therefor the only reason why you can call it 1xx% H2SO4 is the fact, which you have already written. It is capable to produce 1xx% H2SO4, when water is added.

ezekiel wrote:
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And, finally yes you ca nget over 100% of something. Didn't you ever do GCSE level maths?
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I don't know, what 'GCSE level' is, but you are right. 150g of pure water is 150% of 100g pure water. If you earn 30$/hour and me only 10$/hour, you earn 300% of my wage. But when talking about concentration, it is always lower or equal to 100%. It is quite simple: c=A/(A + B + .....). Now use your level of maths: can "c" be higher than 1? You are a 101% dummy, aren't you So don't pontificate others, if you aren't sure what you are talking about...

[SantasL.Helper]

Originally posted by megalomania
Demolition
On the other hand 100% pure water is quite normal. It will never be 100% practically, but number of 9's(99,99...) can be high even at the room temperature. You just redistill it so many times in absolutely pure tin apparatus that almost nothing is dissolved in the final product. The conductivity of pure water is VERY low, because only a small number of ions exist there. For example it is VERY difficult to obtain pure water with pH 7 by normal distillation. pH of normal distilled water which you buy at the gas pump is ~5-6, because of CO2 dissolved in it.

No, water has a very low conductivity cause it is an amfolyte. The very low conductivity IS caused by the very low presence of ions but those are caused by the reaction H2O <--> H3O + OH which is balanced far to the left. So even 100% pure water would still have a very low conductivity.

As this is an archive file i suppose nobody has been talking about this subject for ages, but i read it an just felt like posting my first post....

Hello you all.

[vulture]

-> The conductivity of pure water is VERY low, because only a small number of ions exist there.

->No, water has a very low conductivity cause it is an amfolyte. The very low conductivity IS caused by the very low presence of ions but those are caused by the reaction H2O <--> H3O + OH which is balanced far to the left.

Ehm, you managed to say exactly the same thing and to sound like a smartass.
Congrats on your first post, since it's highly irrelevant too.

Distilling HNO3 + H2SO4 will usually achieve a higher purity, because this mixture boils more uniformely since there is no clogging (from KHSO4) in the distilling flask. So, no bumping boiling and much less decomposition.

I've had numerous bad experiences with a water aspirator vacuum pump because of fluctuating water pressure, meaning that water got sucked back in the receiving flask.
IMHO, if you're not concerned about water usage, use an aspirator and turn the tap WIDE open.
The bloody thing consumes about 400l/hr....

Oh and use one with a flowback protection valve. Nothing sucks like having distilled for hours and then in a moment of unawareness turning off the tap water, resulting in a load of water getting sucked into your freshly distilled HNO3.

[SantasL.Helper]

Originally posted by vulture
->

->

Ehm, you managed to say exactly the same thing and to sound like a smartass.
Congrats on your first post, since it's highly irrelevant too.


Thought he was talking about the water not being pure cause there were substances like salts in it in very low concentration what caused the conductivity. I just said that even if there weren't salt ions disolved in the water, the water would still be conductive.

Thanks for not overflaming me though, first posts are always a bitch... I'll try to keep up with your knowledge guys...

[Mendeleev]

Can anyone describe to me in detail how to set up the vacuum pump distillator :confused:? I don't need to know how to make the actual pump, I just want to know how to connect it to the distilling rig, and furthermore where to connect it to; the initial flask, the receiver, where?

Thanks

[SantasL.Helper]

You can connect the vacuum source to a vacuum adapter that's located between your receiving flask and the condensor. If i remember right, you just connect a tube to the adapter. The tube is attached to the vacuum pump.

I've seen pics of the setup before but don't remember where... "bah" :( and as i don't have a vacuum setup myself i don't know it very precisely.

Believe there are pics of such kind a setup on rogue already though...

[Milamber]

Check out this link
https://www.rhodium.ws/chemistry/equipment/pictures/distillation_big.jpg

Nice picture that should tell you all you need to know to set it all up.

[Mumble]

If you have an actual vacuum pump, you really should set up a wash bottle or two between the vacuum pump and the apparatus. You don't want NOx getting in your pump and messing up anything. If you have a water aspirator its really not a problem. It <i>may</i> eventually corrode a small amount after running a lot of NOx through it. It will look like this http://albumen.stanford.edu/library/monographs/monckh/060.gif The short tube goes to the vacuum source, and the long tube goes to the apparatus. Make sure the longer tube goes close to the bottom. Any solid glass container will work, use the same basic setup though.

To prevent the suck back of water like Vulture had mentioned, install two on your line. The first should be empty, and the second should have the water. Now, when I say prevent, I mean prevent from getting in the recieving flask. That is mainly only a problem with aspirators though. Actually you could use an empty jar on the line to collect any water sucked back through the aspirator. It was unclear if water was sucked back through the aspirator or wash bottle in Vulture's post. The empty jar is all you need with an aspirator though. Keep the tubes shorter too, like only half way down for the longest.

[Mendeleev]

Thanks for all the help guys :D, but I've come up with yet another question. The two most widely discussed methods of nitric acid distillation on the forum are HNO3 + H2SO4 vacuum distillation and KNO3 + H2SO4 heat distillation. The HNO3 + H2SO4 vacuum method has been said to give a more pure product. Well, I was wondering if you could achieve the same purity product doing the KNO3 distillation method if you did it under a vacuum like the HNO3 + H2SO4?

[Anthony]

If people have the use of a vacuum still then they use it for XNO3/H2SO4. Vacuum isn't restricted to HNO3/H2SO4.

[knowledgehungry]

Vacuum merely allows the distillation to be carried out at lower temparatures, thus less HNO3 decomposed and NOx formed. HNO3+ heat--> H2O+NOx. I know many people here now this(at least they should) but im just clarifying since we have had such a rapid increase in newbies.

[McGyver]

If a vacuum pump is necesary, maybe it can be made out of a PC fan. You would just need to get some hose for the right diameter. A vacuum cleaner motor would probably work the best.

[Anthony]

Sorry, there's no way a PC fan is going to pull a useful vacuum.

[Ezekiel Kane]

McGyver: I've stacked a few Sunon 80mm fans along the front of my Enermax FS-710 case for intake, and still barely get enough pull to stick a piece of paper along the front of the computer. Even those huge ~200 mm Delta fans wont pull enough to vacuum distill nitric acid. Just get a used vacuum pump.

[Guerilla]

Get a vacuum aspirator, its cheap and decent for distilling HNO3 (~700mmHg with a water flow of 6l per minute). If you want to save water, just recirculate it with a separate pump and you are only consuming electricity. Its of course a better option too, if the flow from your faucet is weaker than that of the external pump.

[McGyver]

I have a PC fan for the CPU which spins faster then 5000rpm, the noise takes time to get used to. Im sure it would suck some of the vapor out if the hose and the fan are air tight. This will probably only work if the fan is directly connected to the flask. It wont work as well... but it should work a little.

[Anthony]

I'm afraid that speed and noise don't qualify a vacuum source :)

Feel free to try it, we're just letting you know that you'll probably be dissapointed with the results. You could always attach a simple tube to the fan via some paper/tape ducting and see how far you can lift water up the tube. That'd give you a vacuum rating.

An old vacuum cleaner would be far superior IMO. Aspirators are also cheap and easy to make.

[Mendeleev]

How well will this distillation apparatus work: http://scientificsonline.com/product.asp?pn=3081474 This is obviosly without vacuum, so can anyone give me an estimate of the achievable concentration by KNO3 + H2SO4 distillation? Can anyone also tell me where they buy their glassware, e.g. vacuum adapter, 3-way adapter, etc. for the distialltion rig on this link: https://www.rhodium.ws/chemistry/eq...llation_big.jpg that Milamber showed me?

[Mumble]

I got my 3 way adapter and vacuum adapter from www.unitedglasstech.com They seem to be pretty nice. Prices are not bad compared to elsewhere. I got two 1 L flasks and a 400mm liebig condenser from a guy I know. Then I had to go and break my condenser. So I need to get a new one or try to melt it together. Occasionally you can find some idiot who has no idea what he has, selling 600mm fractionating columns for $10 on ebay. Probably goes with all the other supplies.

As far as the apparatus in the link, I don't think it would work for nitric acid. The rubber stoppers holding it all together will be dissovled by the hot Nitric vapor. If you could tool your own teflon stoppers it might work. The condenser doesn't look to efficient either though. You're best bet for nitric acid is all glass if you want an "official" apparatus. If you just want nitric acid, you can probably rig one up. I know there plenty of info about that in this section.

[Mendeleev]

Tis' I once again. This time I was wondering if there are any OTC sources of urea. Will piss work? By the way mumble, thanks a lot for the glass site, its great :D.

[blindreeper]

Mendeleev, are you being serious asking if there are any OTC sources of urea? Check the Great OTC Survey thread. But since I havn't linked it for you I will tell you anyway. In most supermarkets and garden shops sell 5kg bags for about $10. The other is in instant cold packs, its either NH4NO3 or Urea :)

[Mumble]

Personally all I can get around here in cold packs is Urea. I would recomend going the fertilizer route. It much more cost effective, and there is no diference in purity. It should say 46-0-0. Its the highest nitrogen % of all common fertilizer sans liquid ammonia.

Its just a personal thing, but if you're going to use it to remove NOx from the nitric I purify it first. If I don't it gets darker that it was initially. It seems like there is a large amount of dirt mixed it. It makes a dark brown solution. It is fairly easily removed by filtration, then recrystalisation. The urea is only slightly yellow tinted afterward. After purification is just fine for removal of NOx and makes it nice and clear.

[blindreeper]

Strange that you urea is an off colour. My bag I got was 5 kg full of the whitest white prills. It forms a totally clear solution with water when I made urea nitrate. Back to nitric acid now...

[Mendeleev]

Since a vacuum pump reduces the temperature needed to evaporate nitric acid, at what temperature should I heat the acid if I am doing distillation with a water aspirator?

[Mendeleev]

I was also wondering what is the maximum practically attainable concentration of nitric acid without a vacuum.

[Rosco Bodine]

What is the highest attainable concentration of nitric acid for
an atmospheric distillation would exceed 97 per cent , because
97 per cent is attainable as the predictable result using drain
cleaner grade 92.5 per cent sulfuric acid and once recrystallized
sodium nitrate fertilizer for the precursors . For example ,
from 600ml of drain cleaner added to 600 grams of sodium nitrate
in a two liter round bottom flask and mantle , distilling into an ice water
cooled 500mm Graham condenser equipped with a 500ml receiving
flask which is vented by an interposed side takeoff vacuum adapter ,
equipped with a vent line to carry away any fumes fitted to the tubulature ,
the product will be 375 grams of D. 1.501 pale yellow nitric acid (97 per cent)
The yield on a percentage basis is about 84 per cent at this point
( based on sodium nitrate ) , but pushing the reaction to completion
results in an elevation of temperature and a reduction in the quality of
the acid distilling over , so the distillation is generally terminated
early if the quality of the product obtained is more important than
maximum yield . The dynamics of the reaction are predictable , so
the heat should be brought up slowly and when the mixture does
begin to boil , the heating should be reduced because the reaction
proceeds from its own heat to an extent , and it is easy to overshoot
the boiling point and create a boilover if the reaction is hurried in
the early part of the distillation . Excessive heating is not required
and must be avoided , low and slow heating just sufficient to produce
a smooth distillation is necessary for producing good results .

[Mendeleev]

NH4NO3 works for nitric acid distillation, just as well as KNO3 right? Because I have a much more plentiful source of NH4NO3 than I do KNO3. Thanks.

[Blackhawk]

Any common nitrate salt should work, afterall you are just going from

xNO3 + H2SO4 - HNO3 + xSO4

It's not particularly important what 'x' is

[babou007]

That's wrong, BlackHawk
H2SO4 + XNO3 = HNO3 + XHSO4

[Rosco Bodine]

Mendeleev ,

Excellent question about substituting ammonium nitrate .
I have half the answer .

For making azeotropic nitric acid 68 per cent which
distills at about 120 Centigrade, Ammonium Nitrate
is actually preferred . There is added to the mixture
sufficient water to account for the water to be contained
in the azeotropic nitric which will result , plus a few
more per cent of theory because the dehydrating action
of the sulfuric tends to disrupt the azeotrope in favor
of more concentrated nitric being produced . A nearly
100 per cent yield of azeotropic nitric acid 68 per cent
is the result from a very smooth and rapid distillation
where the residual mixture remains a liquid
having no precipitated acid sulfate salts at the
120 degree C temperature of distillation .

However , I have never tried to distill more highly concentrated nitric using ammonium nitrate . It may work fine , but there are some concerns about decomposition using ammonium nitrate under the more extreme
conditions which has inclined me to prefer use of sodium nitrate instead .

Maybe someone else here has experience with producing higher concentrated nitric directly from relatively anhydrous mixtures of sulfuric acid and ammonium nitrate. It may or may not work the same as when using metallic nitrates .
I would also like to know the full details of anyones experiences using ammonium nitrate .

If there are any decomposition issues with distilling higher concentrations from ammonium nitrate , then there could be used a two step distillation , where the azeotropic nitric acid is first made using ammonium nitrate , and then mixed with sulfuric acid and distilled a second time to increase the concentration further to 98 per cent or better .

[Microtek]

Before I began to concentrate 62 % HNO3 with H2SO4, I used AN. It gave a reasonably good product which worked for producing RDX without removing NOx. That said, it did contain quite a lot of NOx ( much more than when using 62 % HNO3 ), but I cannot say how it compares to distillation of NaNO3/H2SO4, as I have never used metal nitrates for nitric production.

[Rosco Bodine]

Microtek ,

When you distilled nitric acid from sulfuric and AN , what
concentration and grade of sulfuric did you use ? Did you
density test the nitric to determine its concentration ?
Were there any problems of surging , or evidences of
decomposition ?

I have distilled nitric several different times using good
equipment and careful control and it is normal for the
nitric to have a bright lemon yellow color , almost a dayglow
flourescent , yet pale yellow colored tint , if that makes sense .
The color is like that bright "Easter yellow" on the little sugar
coated marshmallow candy chicks that are sold for childrens
Easter baskets . The same effect as the bright yellow of picric acid
solutions . If the distillation is hurried , the color intensifies to
a distinctly red rust color . I would speculate that the same
impurity is responsible for both the red and the yellow tints
and it is simply a matter of the concentration of the impurity .
Anyone who has worked with dyes has probably noticed that
concentrated yellow dyes appear more red than yellow , yet
when diluted in solution appear quite distinctly yellow . The
color property is related to the state of subdivision of the color
producing component in solution . Lead styphnate crystals are reddish brown , but drop a few crystals into hot water and the dilute solution is bright yellow . This illustrates the effect of color density causing an actual color shift with concentration .

The yellow colored nitric is produced when either azeotropic nitric acid
is produced from drain cleaner 93 per cent sulfuric and AN plus water sufficient for the azeotrope , or when 97 per cent nitric is produced using sodium nitrate and the undiluted drain cleaner sulfuric . In spite of the coloration , both concentrations of nitric seem to be adequately pure for use in synthesis without further purification . The products I describe are the result of distillations at normal atmospheric pressure , done in a closed but vented system . Comparison with vacuum distillation showed no improvement significant enough to warrant the added trouble of vacuum distilling so
I always distill at atmosphere to keep things simpler .

A few times I have seen it mentioned that adding a small amount of silver nitrate to the nitrate acid mixture at the beginning of the reaction improves the process . The method
is supposedly ancient , going back to the alchemists . I have not tried the use of silver nitrate as a catalyst for the process
so I can't say if this is effective nor do I understand how such
a silver catalyst may work to improve the process . If anyone else has any information regarding the usefulness of silver nitrate , please share any details . Thanks .

[Rosco Bodine]

There is a German patent which describes the production of nitric acid
from ammonium nitrate and sulfuric acid . The English translation
of the patent could be very helpful information for this nitric acid
special project section if anyone can do the translation .

See DE280967

[SantasL.Helper]

Guys, on distilling nitric acid a couple of weeks ago, one of my stoppers located on the top of my distilling flask melted away due to the nitrous oxides. Resulting in now an open output/input hole being there. Is there a matterial other then glass that i can fill that little hole up with that won't be attacked by the nitric acid gasses nor nitrogen dioxide gasses?

[blindreeper]

Not much besides glass resist nitrous oxides and nitric vapour. If the hole is where the still head is located and the thermometer is inserted (top of still) could you not just go and buy some plumbing tape (poly tetrafulroethylene aka teflon) and wrap the thermometer with it to make a plug? Or if it's a differnt place, I am sure you can make some sort of plug/ball of teflon tape to make a plug. PTFE tape is cheap ($1.50 AU) for a 10m roll 1cm wide, may be a good option.

[Mumble]

Make sure to get enough layers on the stopper if you're going the wrapping method. When I was distilling with a teflon wrapped stopper back a few months ago, the nitric acid would actually soak into the teflon. Now my stopper is rubbery on top like it should be, and rock hard on the bottom, where it would of had contact with the nitric vapors. There wern't a ton of layers, but there were still enough to protect from melting. It fits in the top nicely now though.

[Mendeleev]

A good place to buy cheap vacuum pumps is www.sciplus.com they're in the motors, blowers, pumps section. $10-30. Could anyone give me an assesment as to how effective they would be?

[SantasL.Helper]

How long will the teflon layer on the stoppers resist the vapours? And isn't it going to leak into my mixture?

[knowledgehungry]

The teflon should resist the Nitric for quite a while, heat is what does the teflon in in my experience.

[gliper]

I had a doller store tefflon pot and my 85% wild guess sulferic eat right through the non stick lare in 12 seconds. As I don't wont to wrek more expencive pans I just use glass now Takes longer but cheaper.

[Mumble]

All it takes is a minute scratch, and the sulfuric can get underneath the coating. This would cause gas production, removing the layer from the pan. At the dollar store, I doubt they have the utmost quality teflon lined pans in the first place. Are you absolutly positive it was teflon to begin with? One might try a spray on teflon product for lawn mowers I believe. Well, thats what ours is for. Keeps the grass from sticking to the underside. Anyway, you could spray on 5 or so layers. This might even work with an el cheapo pan from goodwill.

[SantasL.Helper]

I've distilled my 53% nitric acid up to a higher concentration by distilling it twice with a double amount of concentrated sulfuric acid. I distilled it at about 80 degrees celsius gas temperature under normal atmospheric presure.
Problem: my gained fuming red nitric acid's volume was 83 ml and weighed 131 grams thus having a specific weight of about 1,578 kilogram/liter. Now 100% nitric acid has a specific weight of about 1,52. How on earth can my acid be 1,57?!?!

[Dave Angel]

Santas, if it's not down to error in measuring equipment, then it could be that the dissolved NOx is raising the mass of the acid. I believe that the 1.52g/cm3 is the data for white nitric acid.

[simply RED]

The measurement is not wrong...
Every method used has error. Positive or negative. Only very good methods have 0,0X accuracy. So you must conduct your measurement very much times and apply statistic.

[SantasL.Helper]

I'd go for the raise of weight by the NOx as expected, acid was dark yellow and fuming brown/yellow gasses

[Dave Angel]

I've just been doing a bit of searching and found that 100% pure anhydrous white nitric acid should have a density of 1.522 kg/m3, mp -41.6C, bp 84.1C, and should be kept below 0C to prevent decomposition into NOx and water. I think I'm gonna start storing my nitric in the freezer.

A definition of red fuming I found was where the product contains 'more than 17% NO2 with a density of more than 1480 kg/m3'. The trouble is this could be 70% HNO3 or 100% HNO3 with dissolved NOx so I'm now not sure if dissolved NOx raises or lowers the density.

I guess the best method to be sure of your concentration would be to get it as white as you can and then measure the density.

[knowledgehungry]

Dissolved NO2 raises density IIRC.

[hodio]

Have you ever heard of distilling the azeotropic 68% nitric acid by extractive rectification using Mg(NO3)2 - Solution? Nitric acid with a concentration of 99% HNO3 and more can be produced colourless and free of NOx.The column operates at atmospheric conditions.I dont know the specifics of the process but it sounds very interesting to me.It's called MAGNAC-Process .

[snuk5]

A little about vacuum pumps for the purpose of distillations:

I have a nice single stage rotary vane pump from Brandt, but I would not dream to use it for distilling nitrous and acidic vapours. (Should only be done using a special oil)

So that would leave the old water-jet pump. I had two models. A modern PE injection moulded job and an old machined brass contraption. Both used vast amounts of water.

So I took the brass one and soldered a piece of that thin copper tube that one finds in a fridge, in the jet part. And in the outlet, I soldered a slightly wider tube that I tapered to widen at the upper end.

After a bit of experimenting with the distance between these parts I found that the vacuum was as good or better, as obtained with the original version, whilst using less than 20% of the water. (less than 3 millibar above the –theoretical vapour-pressure , at the particular water temperature)

If the pressure is high enough and with the appropriate orifices, the ultimate vacuum is independent of the rate of water flow. The only thing that increases with increased water consumption is the rate of gas removal. (No objection if you have no leaks or excessive generation of gases in situ.)

So if you want to save a lot of water and wait only a minute or so longer before starting the distillation, modify your pump!

[snuk5]

With reference to getting vacuums from using CPU fans, vacuum cleaners, modified bicycle pumps or attaching your distillation to your car’s carb and revving your engine etc., I would like to mention that it requires a serious vacuum to get a meaningful depression in your boiling pnt.

Doing the job on Mount Everest would be better than most of the above and would still be pretty useless (especially considering the input of the cost of your sherpas to schlep it all up there - lol)

I’ve got a neat little “boiling point – pressure nemograph” that shows the relation between the boiling point at atm. pressure and the expected boiling point at any prevailing vacuum. (down to .005 millibar).

If you have a known boiling point and a ruler, you’ll be able to interpolate what to expect. –I’ve found it a great tool!

I must have it scanned and on a CD somewhere; if anybody wants it, drop me a line.

Speaking from memory, I recall that the partial vapour pressure of water (@ 20 degrees) is around 17 millibar, so an ideal water-jet pump would give you the same vacuum.

17 millibar = {(1033.6 – 17) / 1033.6 } * 760 = 748 mm Hg.

Such a vacuum would allow one to boil water at a temperature of – well 20 degrees of course!

[snuk5]

About Oleum.

I’ve got still a liter of the stuff (Carlo Erba, AR grade –cost a blooming fortune)

(When bought by the 200 liter it is way cheaper, but that was too rich for me.)

They call it oleum because that’s the Latin word for oil –it is way thicker than normal 98% H2SO4.

This stuff is seriously greedy for water! I bought it at the time for making acetone dicarboxylic acid and got some in my face when things went wrong. My method for ducting off the carbon monoxide gas did not work out so well… (Thanks to the glasses and bicarb I still have eyes and a face! Maybe the fact that it was very cold and had a lot of citric acid in it helped as well) Anyway the next time it went OK.

I digress; oleum is made by dissolving SO3 into H2SO4, SO3 being the Acid Anhydride of H2SO4. Now what has this to do with concentrating HNO3?

Well adding oleum to your nitrating mixture instead of 98% H2SO4 puts less strict criteria on the concentration of your HNO3.

One hundred gram of oleum (20% SO3) will draw water out of HNO3 (aq) to the amount of 6.5 gram, so as to get to the strength of 98% H2SO4.

Or what of cooling azeotropic HNO3 and simply bubbling in SO3?

If we’d be able to get a cheap and reasonably readily available source of SO3, we could forget about concentrating HNO3. (If pigs……. etc)

SO3 is made by leading SO2 + O2 over hot vanadium pentoxide. (Electrically heated stainless steel pipe?) Any unoxidized SO2 would simply not dissolve and escape.

SO2 is dead easy to make

Anybody has some vanadium pentoxide?

Should I dissolve my drop forged tool set in HNO3 and extract the vanadium?

[hodio]

If you bubbling SO3 in azeotropic HNO3 and suppose you get the 32% of water (azeotropic) out to form H2SO4 you gonna have a lot of problems,like a very efficien cooling system and dont forget that SO3 can be very dangerous .If you find a easy way to make pure SO3 (which i doubt) i would
cool it to get it solid in an ice bath,but I would put it in my H2SO4 98%.

Now the reaction of making SO3 from SO3 is:

SO2+1/2O2=SO3 and is prepared at 400 c in presence of vanadium(V)oxide catalyst

in lab can be made distilling a mixture of concentraded sulfuric ac. and phosforus(V) oxide .

In both cases it sound very nasty to me,and i have to say that im jealous you have pure oleum for your synthesis!

[vulture]

Vanadiumpentoxide is bloody expensive. The trouble is, you need a thin active layer disposed on a large surface of Al2O3 for example. This isn't much of a problem with elemental metals, because that can be done by hydrogen reducing etc... But V2O5 is a insoluble oxide and thus won't be easy to deposit in a uniform way.

Or what of cooling azeotropic HNO3 and simply bubbling in SO3?


Ever looked at the hydration enthalpy for SO3? Your HNO3 solution will boil and decompose in seconds and explode in your face if you're looking funny at it.

[Marvin]

A little platinised rock wool would probably work wonders here instead of vanadium pentoxide. SO3 tends to form a thick mist with water, rather than dissolve, I suspect it might do this with nitric acid also. Its dissolved in conc sulphuric industrially, and this is diluted with water later to get back more conc sulphuric. The biggest problem I see though is that instead of simply not dissolving, any SO2 not oxidised will reduce the nitric acid, something less than desirable. I think dissolving SO3 into conc sulphuric is by far the best bet. Maybe in small amounts freezing out the SO3 would be possible and adding this to highly chilled nitric. Rather exothermic though as vulture has said.

[hodio]

In one of my (few) posts about nitric ac. i pointed out a metod to obtein conc. nitric acid using magnesium nitrate,since that i did some searching and i found more specific data:

CONCENTRATION OF NITRIC ACID USING MAGNESIUMNITRATE TRIHYDRATE

A warm solution of 69.7 grams of magnesium nitrate trihydrate and 50.6 grams of 70% aqueous nitric acid is cooled stepwise and filtered at each temperature point. Solid magnesium nitrate hexahydrate is recovered in the following amounts: 35.31 grams at 35.degree. C., 12.05 grams at 20.degree. C., and 6.18 grams at 0.degree. C. The recovered 98% nitric acid filtrate (16.42 grams) is suitable for use in aromatic nitration reactions.

Unluckily in this moment i cant attempt to get it done(my lab has gone!but Im working to rebuild)
so i would like to know if it's suitable in field labs.

[powdermunkey]

A cheap and easy source of useable vacuum pumps is old refrigerators. The pumps will pull a very useable vacuum- typically down to about 10 mT. I go to a metal recycling center and buy pumps for about 62 cents a pound. Nitric oxides will eat the insides of the pump eventually. Would it be feasible to put a container of slightly moistened baking soda ahead of the pump, to catch the fumes? Also, isnt polyethylene resistant to HNO3 and its vapor, so that I could cut a plug out of a PE cutting board, for instance? What sort of protective gear is advised while distilling concentrated acids? Thanks all. P Munkey.

[Dave Angel]

I use a solution of sodium hydroxide in water to bubble my fumes through, that works well but remember to use a buffer flask in case of suck back!

As for safety gear, always wear your goggles. I also put my respirator on when disconnecting the flasks after distillation and use nitrile gloves to handle the cool parts, thermally insulated gloves to handle the hot flask. If you don't have a lab coat then some old clothes will do. Standard lab safety equipment really.

[vulture]

Hodio, that is rather interesting. I did know that Mg(NO3)2 is used to break the azeotrope (more easily recycled than H2SO4) when distilling, but I didn't know it could be done this way.

I assume anhydrous Mg(NO3)2 will work even better?

EDIT: If you really want to try the SO3 method, it might be advisable to produce it by calcinating a sulfate.

[snuk5]

Hmmm, I have to confess that I’m quite convinced that the production of SO3 is better reserved for the production of oleum -when one can’t buy it. (Or afford AR grade!).

At any rate if we do a bit of molar maths, we’d find out that the merits are but relative. H2O is but a light molecule and it takes a lot of Oleum to convert it to H2SO4.

I was just bouncing off an idea that was not well thought out. The comments made in reaction to my post have been duly noted. Even a less than perfect idea can lead to useful comments!

Having said that, I do not think that the strongly exothermic nature of the process is an objection. With enough lengths of high grade stainless steel (eg.316L) coiled tube, and cooled water-flow any amount of heat can be dispensed with.

BTW. I found this a nice way of cooling the acid mixture when making larger amounts of NG. To aid the bending, I packed up 10 mm tube of stainless steel tube with salt and stoppered the ends. Then I coiled it in a coil of about 115 mm diam. Then I flushed out the salt with a smaller tube. Use soft / annealed (pref. seamless) tube.The Stainless steel did not perish, due to the moderate / lower temperatures and the high concentration of the acid. In fact I used even a stainless steel pot as my reaction vessel.

Regarding the HNO3 concentrating; the MgNO3 process is one of the preferred methods in industry. They actually like to use it in the form of a saturated solution (i.e added water!) as this is easier handled than solids.

I reckon that for the home lab both the H2SO4 and the KNO3 methods are also quite acceptable but they have their drawbacks in the equipment department: Good and big glass is expensive and it breaks! The niter-cake (K2/HK-SO4 residue) is difficult to remove at the end of the distillation). The need for a vacuum necessitates both a vacuum pump and leak-free (ground glass) joints etc.

I have never tried it myself, but if I’d needed fuming nitric acid now, I’d try the methelene chloride extraction method.

Can anybody give details about their experience with this process?

[JoeJablomy]

I've never dealt with these guys, but they seem to sell some interesting stuff, including the aforementioned vanadium pentoxide.

http://www.micronmetals.com/vanadium_pentoxide.htm

[vulture]

I have never tried it myself, but if I’d needed fuming nitric acid now, I’d try the methelene chloride extraction method.

Can anybody give details about their experience with this process?


Please, don't make yourself suffer from fatigue caused by searching:

http://www.roguesci.org/theforum/showthread.php?t=3157

:rolleyes:

[Jetex Kid]

The information on magnesium nitrate may be found in US Patent 5,012,019, along with good news, such as that MN+6H2O regenerates to reusable MN+3H2O at between 120C and 140C.

Also, MN is inexpensive and available at pyrotechnic houses if you are not a DIY type. I suspect that completely dehydrating MN would damage the basic molecule, perhaps driving off oxygen. Otherwise, it might rival P2O5.

Regarding the creation of new nitric acid via the sulfuric acid-and-nitrate route, it is difficult to distill sulfuric from the final mixture of sulfuric and nitric acids. If one used pure sulfuric acid and an excess of nitrate, the only liquid present at the end would be NA, thus eliminating distillation. Comments?

[vulture]

is difficult to distill sulfuric from the final mixture of sulfuric and nitric acids.

Huh? What's your point? Nitric acid is much more volatile than sulfuric acid and thus the NA will distill over, not the sulfuric acid. Using excess nitrate will cause a nice goo to form in your heating flask along with horrible bumping.

[akinrog]

Maybe somebody else suggested this before. (I searched forum but could not find anything directly describing this.) I saw this method on rhodium's site (http://www.rhodium.ws) though I don't know exact URL.

Although it was not covered in the rhodium's site, in past SO3 was prepared by heating Fe2(SO4)3 to decompose it to FeSO4 to give off SO3. Reaction is something like this
Fe2(SO4)3 -> 2 FeSO4 + SO3 + 1/2 O2.

At rhodium's site, SO3 is prepared by using KHSO4. First it is heated to give of H2O (which is discarded) and Potassium Pyrosulphate (which remains in heated flask) and then further heated (this time more vigorously) to give off SO3. The SO3 released was collected in a flask cooled by some sort of cold bath. SO3 may be used to create oleum which is as far as I can see highly wanted by some members. ;)

IMHO, iron tri sulfate procedure is more feasible for me which during my high school years is contained in the chemistry textbooks, as far as I remember. Since you may use cheap battery acid to create iron trisulfate, dry it and decompose it into SO3 by heating. Since obtained Ferrous sulfate is recyclable, you may use it for obtaining ferric sulfate again and decompose it into SO3.

HTH

[Roy Paci]

So sorry for the stupid question, this is my first post. I distilled nitric acid. But it gelatinizes cotton only when it is mixed with 98% nitric acid. So I guess it is not enough concentrated, even for alchool nitration, am I wrong? It is clear orange and it fumes very light yellow/orange vapours. Thank you for any comment or suggestion.

[simply RED]

and it fumes very light yellow/orange vapours?
Really? At what temperature?

At 0-10 degrees Celsius 95% HNO3 fumes VERY intensively forming totally white fumes. Opening the jar means filling the room with fumes. It is impossible to make RDX with such acid where other people live.
At 10 degrees "absolute" nitric acid fumes red. Opening the bottle releases red cloud in front of your face! Never keep such acid at room temp!

[Roy Paci]

Thanks red!
An increase of the WHITE fumes(fumes seem more effectively white) occurs when organic stuff and whatsoever get close to the surface of my acid. Do you think that checking the density would be a reliable way to get a correct measurement of the purity of the NA?
Unfortunately I got my knowledge about red, NO2 fumes :eek:

[nous]

which i came across from my fellow bees from the hive..

Nitric acid

Into a 250ml flask with stirbar, set up for distillation, were carefully1 introduced 122g 93% H2SO4 (1.16mol), 100g NaNO3 (1.18mol) and 74ml H2O. The flask was heated on oil bath with stirring and a yellow liquid was distilled off (128C)2. When the distillation speed slowed considerably and the temperature in the stillhead dropped below 100C a first fraction was taken (96ml, 126.85g), 37ml H2O where added and a second fraction was distilled off (36ml, 37.83g). Both fractions were titrated against NaOH to give 10.8mol/l resp. 1.3mol/l3. The two fractions were combined and diluted to 382ml to give 382ml of an 18% HNO3 solution. (Yield: 92% from NaNO3)

Notes:
1: And I mean carefully, this gets _very_ hot.
2: At first some nitrous oxides (orange gas) are produced. But the amounts are so small that there is no danger whatsoever.
3: 4g NaOH were dissolved in 1l H2O to give a 0.1N solution, 1ml of reaction mixture was diluted to 100ml and 10ml of this solution were titrated against the NaOH solution. Usually the NaOH itself would have to be titrated against an acid of known concentration, but the results fit very well with the measured densities.

[simply RED]

nous, this is not for here, this is for a thread: how to get diluted HNO3!

Yes, correct masurement of the HNO3 density gives reliable data about ist concentration +/-3-4%.

[Mendeleev]

I recently came upon a pdf describing an industrial process for production of +98% nitric acid without distilling with sulfuric acid. The Ostwald process is a three step for making nitric acid out of ammonia and oxygen:

4 NH3 + 5 O2 ---> 4 NO + 6 H2O
2 NO + O2 ---> 2 NO2
3NO2 +1 H2O ---> 2HNO3 + 1 NO

This yields around azeotropic acid. However the DSN (Direct Strong Nitric Acid) method stops at the second step, producing a lot of NO2 and some dilute HNO3. The NO2 is then condensed, pressurized and cooled forming N2O4, which reacts with oxygen to give nearly anhydrous nitric acid. The pdf describing it is www.epa.gov/ttn/catc/dir1/nitric.pdf . My question is this, N2O4 and O2 will give two nitrate groups, where do they pull the hydrogen out, or did the paper simply omit that part? Also, it mentions that the DSN process is not commonly used in the United States. Why?

[akinrog]

The pdf describing it is www.epa.gov/ttn/catc/dir1/nitric.pdf.

Sorry but this link does not work for me.

Can you check it please? I want to examine the pdf.

[pdbm]

Has not anyone tryed N2O5 + H2O = HNO3 + heat
u just need to get the amounts right, but Not many people have N2O5?
:confused:

[Mendeleev]

I just tried it and it worked fine, it begins to automatically download the pdf.

[tiac03]

I don't know how useless this information is but I was reading a chem book and it had a table of acids.. so since we or you's are talking about Nitric acid I figured I would post the information from the table.

Density g/ml at 20 deg C [1.50]
Melting point deg C [-42]
Boiling Point deg C [86]
Solubility in water Infinitely soluble
Amount in concentrated solution wt % [69]

I know I am probably stating stuff y'all know but figured it is better to post something twice (or more) than never at all.