Nitric Acid Synthesis

... nice (!), only the direct heating by the spiral might be a bit harsh ... and your beautiful retort might be history after a while ...

A bath of molten tin might be a good heat-transfer-medium for such a purpose: Tin is known to have quite a low vapor-pressure, and is therefore used in industrial manufacture of float-glass, where liquid glass rests on a hot tin-bath ...
==> Only the tin should be clean, no lead or arsenic or antimony in it ... !

Quote: Originally posted by Mildronate

Here you can see my retort, its made from 1liter flash and glass pipe. I use it only for nitric acid.

thats true but its because retort was wet from water

Carefully indeed, but if you meet that requirement it's fine. The temperatures involved here are well below the melting/decomposition temperature of ammonium nitrate (210°C or more) as long as you use a uniform heat source and boiling chips. I did this too and it works very nicely giving near perfect yield. I used fertilizer grade ammonium nitrate and drain cleaner grade sulfuric acid in aqueous solution.

The vapor and reflux inside the column was clear, indicating that no ammonia was being given off from the flask, and the gas scrubber on the vent (which doubled as the condenser cooling water) remained at steady pressure when the distillation had stabilized, indicating that no N2O or other gas was being given off.

Doing an anhydrous distillation under vacuum should be a further improvement.




[Edited on 3-5-2010 by kilowatt]

drying ammonia

Quote: Originally posted by Formatik

... 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.

So yesterday I made some nitric acid. I used KNO3 and H2SO4 and distilled a clear liquid under aspirator vacuum.
The glass was baked in the oven prior to use, the KNO3 was baked in the oven prior to use, and the H2SO4 drain cleaner was boiled on the BBQ till it was fuming, and it was let to cool off to a use able temperature (unstoppered though).
The density of this nitric acid was 1.497 at standard pressure @ 4 degrees Celsius (did not measure room temperature). I assume this to be around 80-85% HNO3.

It was stored in the fridge overnight (at around 4 degrees c) in a ground glass flask with a ground glass stopper and vacuum grease.

Today I decided to re distill it over sulfuric acid to increase the purity. It came over at about 50c. I mixed equal volumes of my HNO3 and fuming h2so4. This time I left the H2SO4 on the grill while it was fuming, and stoppered it with a ground glass stopper while the flask was still hot (maybe 200c), and let it cool to room temperature prior to adding it to the nitric acid. Again, the glassware was baked in the oven prior to use.

I have measured the density of the nitric acid at about room temperature, and it is only 1.477, meaning the nitric acid is less then 90% after I vacuum distilled it from sulfuric acid. I only distilled half the volume of the nitric acid (started with 100ml hno3 and 100ml h2so4 in the boiling flask, and I stopped distillation at 50ml in the reviving flask.

I was under the impression that this distillation should have left me with like 95%+ HNO3. What the hell is going on?

Someone suggested that water vapor might be getting sucked in through the aspirator, but I find that hard to believe, as other members on this board seem to be getting 95+% hno3 using aspirator vacuum.

The KNO3 I am using is pyro grade.


Am I not heating the H2SO4 enough? I heated it to a point where it was spewing thick, choking, unpleasant fumes.
What is the secret to performing this distillation?
And the scale I am using is a MXX-123, which claims to have a uncertainty of 0.663 milligrams... .
The volume is measured using a 10ml graduated cylinder.
what the fuck this shit??!

[Edited on 2-6-2010 by Chainhit222]

Quote: Originally posted by hissingnoise

Quote: Am I not heating the H2SO4 enough? I heated it to a point where it was spewing thick, choking, unpleasant fumes. When boiling down dilute H2SO4, a choking steam appears long before the last of the water boils off. You should continue the boiling until the appearance of the fumes changes from a heavy steam to a much thicker, solid looking white vapour (SO3). This occurs when the temperature goes over 300*C. . .

As hissingnoise said, heat the sulphuric till you choke from the fumes, and your mom is yelling at you that you ruin the whole backyard

When it smokes intensely condense some of the fumes to a cold glass plate and touch it with some organic, like tissue paper, if the paper char, continue to contentrate it for further 15 minutes or more.

If I were to make 98% H2SO4 from ~90% drain opener, I would vacuum distill 1/3 of the acid and discard it.

For relatively contentrated nitric ~95% you do not need to use 98% sulphuric, baking flask, drying KNO3 etc, just start to distill over the HNO3 from the reaction mixture and discard the first 1/3 of it. or use it for something else that wont require cc nitric.

I just posted a video to youtube where I made HNO3. watch it if you'd like. comments and criticisms welcome....I think I did the math right.

http://www.youtube.com/watch?v=n13n4PoF4L8

nitric acid

guys, I was just doing a distillation. But after distilling 150mls of 70% HNO3 with 300ml of 99% H2SO4, I got a yield of 20mls, at which point nitric stopped coming over the still head and down the condenser.

The 20mls I did get was 95-96% concentration, burnt a small crater in my hand when a small droplet landed on part of the skin that the glove didnt protect. I didn't quite realize the potency of this acid until that happened lol.

20mls for 150mls isn't good enough for my liking. Can you guys diagnose the problem?

I use an aspirator to pull a vacuum in the setup I use. I have a 40cm liebig condenser that I use. The nitric acid I was distilling was boiling and coming over at around 70 degrees, and then it stopped boiling and then nitric acid seemed to stop evaporating, but I think 100mls of nitric acid has left the original nitric/sulfuric acid mix. Has this 100mls of acid or water just been sucked out by the aspirator? I think my joints are pretty tight, and I used 1 wrap of teflon tape to make them more airtight.

I didn't cool the condensated acid with ice, just water that was about 16 degrees.

Here's a vid I made a while back with a similar setup, except the aspirator was bigger than the small glass one I have now.
www.youtube.com/watch?v=yXxSAQFo9ZE&feature=related

How should I go about reducing the amount of acid lost to the aspirator?




I also have a big 25L container of 70% nitric which I bought for $3/L, and I was hoping to use this up by concentrating it with the big 15L container I have of 99% sulfuric which I got at $2.75/L ..... but would it just be better to distill nitric from scratch and have it concentrated that way? If it did it under vacuum, would it achieve a nice 90%+ conc of nitric?

[Edited on 04-07-09 by uchiacon]

Recycling H2SO4

See! Seeee! I told you it wouldn't work, didn't I; Didn't I? Oh but would you listen? Would you???
No! You had to go and be an experimenter.

Hehe, yeea!
I'm an experimenter, can't help it...

Cheap and Effective Nitric Acid Distillation Apparatus

Here is a very simple little glass still I made a year or so ago from common flasks without ground glass joints. The most important part of the apparatus is the Teflon bushing, which can be easily made on a lathe from Teflon round stock of an appropriate diameter. Two approximately eight dollar flasks were used and a piece of glass tubing obtained for free. A piece of Teflon round stock was purchased for $30 which provided enough material for 4 bushings. The center hole of the bushing was bored out slightly oversized and the outside diameter of the section which would slide into the flask was made slightly undersized. This allowed the glass tubing and outer diameter of the bushing to have many wraps of Teflon tape applied so as to give some of the elasticity that would normally be present if a rubber stopper was used and provide a better seal. Experiments showed that the bushing still tended to rise slightly, once the flask got hot, allowing vapor to escape. This was easily solved by applying a few wraps of black electricians tape, to the top of the flask and bushing, which completely solved the problem. The first picture of the apparatus in use is from early spring when temperatures where near freezing and with slow distillation air cooling was adequate. The second picture is from a hot day this summer and the receiving flask was placed in an ice bath. I have ideas for how one of those little $10-12 centrifugal table top fountain pumps could be used to pump the water, or iced water up, over the round bottom flask receiver if extra condensing power was needed.

A steel file may be needed to score the tubing if it needs to be made shorter. A propane torch is needed to heat the tubing so that it can be bent and then annealed.



BTW, I do have a ground glass distillation apparatus, but just for fun and skill development I wanted to build this one.

I probably should have another stopper, a two hole, in the round bottom receiving flask. A smaller diameter piece of glass tubing could extent out of it increasing the cold surface area and acting as an air cooled reflux condenser. This would help reduce the amount of escaping nitric acid vapor as well as probably reduce the amount of absorption of moisture by the nitric acid.


[Edited on 30-6-2014 by Hennig Brand]

Same can be done with a glass alembic or a glass retort...back to alchemistry
Retort
alembic

It cost about 8-15€ to get one (250-500 ml) with a glass roded stopper for easier filling.

Simple is often better.

I always wanted one of those, and actually spent some time looking in the past, but never found one for a good deal here in Canada. I think it would cost me closer to $100 by the time I had one of those little glass retorts in my hands and there would be shipping time as well. I think what I have built is actually better (for me) in many respects, however, with the first being that it can be easily built by just about anyone with commonly available materials. The Teflon will likely have to be ordered, but it is still readily available. It is a very trivial matter to make the Teflon bushing on a lathe, or have someone do it who has access to a lathe. The boiling flask is 1L and it cost $8. With the exception of the glass tubing the apparatus is quite robust and if the tubing breaks it is a trivial matter to replace it. Not much could be done if one of those old fashioned retorts got a crack, or something, unless you are good with glass or know someone who is.

Also, the glass delivery tube could easily be turned into a Liebig condenser (tube in tube) if that was desired. The water jacket could be made of just about anything you wanted (plastic plumbing pipe, etc), because it would not be exposed to nitric acid and nitric oxides only cooling water.


Edit:
Just realized the following thread may have been a more appropriate place to post what I did.
http://www.sciencemadness.org/talk/viewthread.php?tid=15676

I was thinking too, it really is a lot of fun and can provide a lot of satisfaction to make your own equipment. Many people, who haven't developed those skills, would find it very difficult to make their own equipment, if for some reason the commercial supplies were no longer accessible to them.


[Edited on 2-7-2014 by Hennig Brand]

It's just about the amounts, to certain extent. I have several larger flasks, largest one is 4 liters, but I rarely perform any synthesis involving aggressive chemicals on that large scale. Largest I've done on ammonium nitrate and sulfuric acid in a single batch was about 800ml of RFNA output. I apologize if the amounts seem large to some users here but I've got used to measure bulk stuff in metric tons and delicate ones in liters because I work in petrochemical industry operations.

Extra cautions must be taken with larger amounts, naturally. I've prepared my working environment and PP equipment according to the amounts I work with, usually with the worst case scenario in mind, which is, blowing up the reaction vessel.

Quote: Originally posted by Refinery

Largest I've done on ammonium nitrate and sulfuric acid in a single batch was about 800ml of RFNA output

Quote: Originally posted by Refinery

Can one make nitric acid from a nitrate salt and formic acid? In theory, formic acid and (ammonium) nitrate could form ammonium formate and nitric acid, but is the reaction balance high enough to proceed? Whether this process works or not, one must remember that ammonium formate and formamide will form hydrogen cyanide if heated too strongly, so a water bath or other medium should be used, or gasses led away safely. One must now boil off the water from the calcium nitrate. If it contains CaOH, it doesn't matter, because now the Ca(NO3)2 is put into steel pot and heated to over 650C, and now it will start to release lots of NO2 gas. This gas forms HNO3 with contact on water. The yield suffers at least 1/3 because part of the nitrogen is turned into monoxide and it is probably lost.