Homemade Nitric Acid

[LiamPyro]

Hey, I haven't posted in ages but something just popped into to my mind that I've been wondering. A few weeks ago, I distilled some nitric acid from a combination of 110g KNO3 and 60ml 98% sulfuric acid in a retort (for those who don't know, a very basic type of distillation equipment). Everything went as expected, besides one thing. When I first poured the sulfuric acid into the KNO3 in the retort, it began bubbling and a large amount of red NOx gases were produced. Even though I hadn't started heating it, a small amount of nitric acid condensed on the glass. After a few minutes the reaction stopped, and I began to heat the retort and went on with the distillation. Is this normal? I have watched videos on this experiment, and nothing like this ever happens. It seems like maybe nitric acid was forming and then reacting with something, but I don't know what it would be reacting with since my chemicals are pure.

By the way, a note to anyone else producing nitric acid, bubbling dry air through it does an *amazing* job of removing dissolved nitrogen dioxide. My acid went from a rich orange color to completely colorless. If you have any questions, I would be happy to explain further.

Edited March 2, 2016 by LiamPyro

[OldMarine]

I remember in high school we distilled nitric acid for making flexible collodion. Wished I'd paid more attention since I know now that collodion is Nitrocellulose.

[Mumbles]

That initial reaction is normal. The formation of nitric acid and potassium (bi)sulfate is pretty exothermic. The reaction can get hot enough to decompose the as-formed nitric acid. This is also partly why vacuum distillation is popular, especially with high strength acid. I've always added the nitrate to sulfuric acid, and you do need to go slow. Hot spots can be formed, especially as the mixture gets thicker. It seems counter intuitive to a distillation, but you basically need to use external cooling if doing this on a large scale.

[OldMarine]

Mumbles, would it be economically feasible to make your own NC at home? I don't remember it requiring too much gear back in the day but I wasn't paying for it either!

[Mumbles]

That depends for what purpose. It's certainly economically feasible to make NC at home. It's not difficult really. The issue tends to be in the scale. Making 5g of good quality is easy with some basic chemistry experience. I trust with ample reading or coaching, most anyone on this forum could accomplish. Making 50g of the same quality is more difficult. There are thermal controls, reaction time, and just overall larger scale factors to worry about. You would need some pretty extensive experience, and trials working your way up to be able to accomplish this totally successfully. I'd suspect that maybe a dozen or two people on the forum could accomplish this safely and effectively. 500g is an entirely different ball game. Besides the basic reagents, almost everything is different. I've done it, have formal training in chemistry, over 15 years of experience with chemical manipulations including this reaction, but even I wouldn't even really trust myself with it.

 

I've done up to a kilo under the supervision of a very experienced chemist. It's really impressive how much things can change with scale. There are so many things you never consider on a smaller scale. I guess that's why I'm a chemist, not a chemical engineer.

 

Many of the scale factors are related to heat manipulation and preventing runaways, and thorough washing to remove all the acid to prevent degradation down the line.

[Mumbles]

I guess I didn't really answer your question. Economically, it depends on your reagent sources. Given some reagent prices, effort and hazards involved I've always found it more advantageous to just purchase NC and make lacquer for most pyro purposes.

[lloyd]

I'll go with that, Mumbles (and Patrick).

 

The last time I priced 9lb sulfuric acid, I nearly choked! Battery-strength stuff is cheap, but it's not concentrated enough to properly extract the water from the nitration process. I haven't priced HNO3 (conc.) in - likely - 20 years, so I have no idea what it's running.

 

But with all the hazards of handling those stuffs, AND the hazard of not being able to properly stabilize your NC without a lot more work and more chemicals, it just doesn't seem worth the while.

 

I made flash paper for a time -- mostly for fun, but also to learn. But I would not be inclined to do it again.

 

Lloyd

[OldMarine]

I can get concentrated sulfuric acid by the gallon (drain cleaner aka Liquid Fire) but I guess I've got enough on my plate so I'll chuck that notion.

[lloyd]

Patrick,

If it doesn't explicitly list the acid as 9lb acid, it's likely not of the concentration necessary to properly rob water from the forming NC molecules.

 

"Concentrated" has different meanings in different contexts. If you put 9lb sulfuric into a PVC drain, it might well heat up enough (in the presence of the organic plastic) to melt the pipe! (of course, that depends on your application method)

 

So-called 9lb sulfuric acid is as concentrated as economically reasonable to sell, and usually must be obtained from a dealer in reagents, as opposed to other dealers who only use H2SO4 as a tool in other endeavors.

 

Lloyd

Edited March 3, 2016 by lloyd

[OldMarine]

We had a newbie pour a quart of liquid fire into a grease clogged line in a restaurant on the second floor of a local mall. The acid did just as you suggested: it melted the pvc and dumped boiling grease and sewage into a clothing store below.

The smell and vapors forced them to close the mall early and open late the next day.

Thank God for insurance but we haven't worked there again.

I'm happy with the shotshell powder lacquer so I'll let this train of thought off at the next siding.

Edited March 3, 2016 by OldMarine

[lloyd]

I get it. The switch has been thrown over! Just watch the signals!<G>

 

Lloyd

[lloyd]

Just an aside, since you have already dropped this to a "siding"... I looked up "Liquid Fire" drain cleaner, and it looks to be the real deal!

 

I wouldn't trust a human to use that stuff in less than a moon-suit!

 

Lloyd

[OldMarine]

It is some serious stuff. We use it to clean/liquify grease build up and partial clogs in UNDERGROUND CAST IRON drain lines in restaurants and packing plants.

We also had a guy use some at a plastic plant that used aluminium based inks for printing bags. He made a sewer rocket volcano fire bomb.

 

Edit: Now that we have high pressure water jetting systems the acid is only used as a treatment rather than a remedy so hopefully the stupids won't have access to it around our shop and only the restaurant service guys will have it. Don't get me started on muriatic acid in urinals tales!

Edited March 3, 2016 by OldMarine

[rogeryermaw]

I'd have to agree with mumbles. To produce a small amount at home is simple, fun and can be very educational but in no way is it economical. I have a fairly affordable source of reagent grade 98% H2SO4 and nitrate salts can be cheap but to produce any significant quantity of concentrated nitric acid requires a good deal of reagents and a glass distillation apparatus of any quality can get expensive when you include a water pump and decent heating mantle. Even a reliable hot plate with oil bath on the cheap will get close to $100. And don't cheap out on thermometers. Too much heat and you degrade a lot of the acid produced. Then be prepared to work outside unless you have good ventilation as those nitrogen dioxide fumes will corrode a lot of indoor surfaces... ya best to just choose a good smokeless powder and couple gallons of acetone. The commercial stuff already has stabilizers and whatnot to up its storage life etc...ya aside from being able to say you did it, no real reason to make your own.

 

That said, I think it'd be rewarding to sacrifice a bit of strontium nitrate for the process leaving strontium sulfate as a byproduct. You get the satisfaction of producing your nitric acid which has a million lab uses and then could use the strontium sulfate in some red strobe stars with the nitrocellulose you'd make!

Edited March 3, 2016 by rogeryermaw

[Mumbles]

Rather unrelated, Lloyd, do you know what 9lb acid actuallly means? I've seen it in passing, but never really understood it. My best guess is that it was the mass of a half gallon of 95+% acid, plus the mass of the bottle.

 

Liquid fire is a high concentration, though is always darker than I liked. My preferred source was Rooto. It's much lighter in color as-is. I'm not sure if they still offer it though. Both were around 92-95% concentration. I often used as is, but you can boil up to 98%. The color of both gets much darker however.

[LiamPyro]

Thanks Mumbles for the answer. I don't know the price of "liquid fire", but I bought three 950ml bottles of 98% sulfuric acid for a total of $50, including shipping, from a website called Duda Diesel.

[OldMarine]

A quart of Liquid Fire, Clobber or Haymaker (all the same) is around $14. Most plumbing supply houses stock it behind the counter.

[MadMat]

One thing worth mentioning about the sulfuric acid drain cleaners.. They more than likely contain some type of inhibitor (uninhibited sulfuric acid eats up iron very easily). These inhibitors may cause problems with your reaction. Of course, if you guys have successfully used Liquid Fire... never mind

Edited March 3, 2016 by MadMat

[MrB]

Many of the scale factors are related to heat manipulation and preventing runaways, and thorough washing to remove all the acid to prevent degradation down the line.

 

Where is the fun in that first half? We all like smoke, and black smelly stuff.

 

Mum, and everyone else is right. There is no reason most of us couldn't make small amounts at the time, But we are talking tiny amounts, and it's just not worth it. Using ammo-grade stuff is so much easier, and it's not really that expensive. I managed to get a fairly large supply of automotive paints, but i think i'll keep that NC for fuses, and fuse priming slurry, as it doesn't seam to burn as hot as the ammo stuff. Which is sad, given that around here it is not as available.

Never did try pingpong balls, even tho i keep checking the boxes, and they still say "celluloid" on the package, unless you specifically look for "poly" balls. So i suppose they would work.

B!

[lloyd]

Mumbles,

I don't know if the "9lb" moniker is even a legitimate term, or just chemistry slang, or just a convenient coincidence.

 

For truth, a lot of sulfuric acid is sold in 9lb shipping-weight bottles, so I guess that's correct.

 

LLoyd

[rogeryermaw]

One note, if you do get around to making concentrated nitric acid, opinions may vary here but best practice is to store in dark glass bottle with teflon seal. Also, even in a 10°F freezer, I had to vent my bottles once a month. They WILL build pressure over time.

[LiamPyro]

One note, if you do get around to making concentrated nitric acid, opinions may vary here but best practice is to store in dark glass bottle with teflon seal. Also, even in a 10°F freezer, I had to vent my bottles once a month. They WILL build pressure over time.

Where did you buy the bottles? I have been looking around and most options are pretty expensive, they are from professional chemistry supply companies. I tried putting a small quantity of white fuming nitric acid in an erlenmeyer with a rubber stopper just to see if it would really destroy the stopper, within an hour the stopper's edges were "melting" onto the glass and the bottom was pitted.

Edited March 4, 2016 by LiamPyro

[OldMarine]

The ground glass stoppers are what we used in school. Don't remember the flasks but if I recall they had ground faces as well. The large storage bottles were brown glass with some sort of plastic screw top with no visible liner.

[rogeryermaw]

i always just kept any bottles from lab supply i bought previously. CHCl3 and ligroine both came in amber bottles. i had a pretty good stock of them at one time.

 

search amber glass reagent bottle on ebay. you might be surprised. think viton cap seals for good chemical resistance.

Edited March 4, 2016 by rogeryermaw

[WSM]

i always just kept any bottles from lab supply i bought previously. CHCl3 and ligroine both came in amber bottles. i had a pretty good stock of them at one time.

 

search amber glass reagent bottle on ebay. you might be surprised. think viton cap seals for good chemical resistance.

 

Viton elastomer is good for some things but definitely not for everything. Teflon is MUCH better for acids or alkalies and will last for years.

 

WSM