Sciencemadness Discussion Board

Alternative Method for HNO3 Synthesis?

Backyard Blaster - 18-10-2003 at 06:54

Slightly off-topic, but still of interest since HNO3 is involved in so many of the procedures discussed here....
I once read a post on a newsgroup somewhere, where someone was talking about a Jacobs ladder they built. For those of you not familiar with these devices, I will explain: they are basically two metal rods arranged in a "V" shape, and connected to a high-voltage source such as an oil burner transformer. When powered, an arc will start at the bottom and work its way to the top, then start at the bottom again and repeat this perhaps 2 or 3 times per second. If you've seen the original Frankenstein movie, you know what I'm talking about.
Anyway, the poster described how he had sealed this device in a glass bottle, to prevent a shock hazard. He claimed that after half an hour or so of operation, the bottle became filled with dark red NO2!
I'm not sure how credible this info was, but if true, it conjures up some great possibilities. As most of us know, when NO2 mixes with water or water vapour, it turns into that precious acid HNO3. If a person could build such a device, and design it to collect the acid, it would be much easier, safer, and ecomonical than the usual KNO3/NH4NO3/etc + H2SO4 reaction. To me, it sounds a bit too good to be true.....
There are other questions as well, such as what kind of power source the guy used. There are many high-voltage sources that this guy may have used in his Jacobs ladder, some of the ones I'm familiar with are:
Old Burner Xformer : 10kV @ 23mA typical
Neon Sign Xformer : 10kV @ 30mA typ.
TV flyback Xformer : 9 - 28kV @ 1-2 mA typ.
Microwave Oven Xformer : 4kV @ 300mA typ. (not well-suited for this purpose, mainly because they are VERY DANGEROUS!!)
All of these, except for the TV flyback, produce 60 Hz output. The TV flyback typically puts out 15,375 Hz but this is adjustable on some older sets (12 - 18 KHz typical).
Any advice, or comments on this idea?

menchaca - 18-10-2003 at 07:39

there is an industrial process for this althought is only possible in those countries wich have a really cheap electricity such as Norway. The process´s name is Birkeland-Eyde please if you find some interesting information let me know ok?

Backyard Blaster - 18-10-2003 at 15:38

I guess I should have realized someone thought of this before. If not, I could be rich.....
Lots of biographical info on Birkeland & Eyde, but I can't find any specific details on how to construct such a device. My current theory is this:
Construct a device similiar to the one seen on (Brainfever's site), but instead of using the chemical mixture, replace it with the two electrodes. With the plastic "cone" filled with ice water, the heat produced by the arc should cause moisture to condense on the ceiling of the apparatus. HNO3 should form when the NO2 mixes with the moisture. But there are still a couple of potential problems. First of all, the HNO3 produced would probably contain water, and I'm not sure how to remove it (though there's probably a simple answer). Second, once the oxygen within the bottle is consumed, it will cease to produce NO2. Therefore, one would have to design a way to inject fresh air into the bottle every so often.
Obviously it will take a lot of experimenting to figure out a feasible way of doing this, but I've got plenty of spare time......
As usual, any comments would be appreciated.

blindreeper - 18-10-2003 at 17:25

There is a lot of discussion about this method over at the E&W

Mumbles - 18-10-2003 at 20:24

To remove water from HNO<sub>3</sub> all you have to do is mix with Sulfuric Acid and distill. You may have do repeat the proceedure more than one times to get it extremely concentrated. Check the density or titrate against a known standard to get a fairly good idea on the concentration.

If the inital concentration is below 68% you can boil until Nitric fumes are given off, then distill with Sulfuric. Adding Sulfuric and distilling Nitric less than 68% is just a waste.

a123x - 18-10-2003 at 20:35

Yes it is certainly possible to use pretty much any of those transformers for such a purpose. NST's are probably best though since they're typically stronger than OBIT's and flybacks but have a high enough voltage that they won't be a pain to get to arc properly. MOT's have too low a voltage to get it easily set up so that it with arc and then have the arc stretch however would be the strongest if you overcame that problem. Other problems are that it would be quite difficult to get the nitric acid to form and then collect it. Perhaps having the NO2 pumped into a tube along with water vapor being pumped in and then condensing this would work or bubbling NO2 into water. The second problem is that it involves HV and toxic NO2 gas so most certainly is not safer than just distilling. Also this method is liekly slower.

Electric sparks in a NH3 N2 CH4 H20 atmosphere

chemoleo - 19-10-2003 at 17:50

on that note, it's not surprising that NO2 forms. Having experimented with 20kV discharges myself, I know myself how much of nasty gases are produced, just have a sniff above the spark. You will notice ozone, and NO2.
Besides that, there is a very famous experiment by Miller, where he sparked a hot gaseous mixture of NH3, N2 , CH4, CO2 and H20, and this for several days in a refluxing system. Surprise surprise, the output was not so much NO2 but rather complex chemiclas, like more than half of the amino acids (20 in total) that are used by all living entities on earth. This means, electric discharges (like lightening) in an atmosphere of reducing gases (as on prebiotic earth) produces a lot of fairly complex chemicals. The mechanistic route to this is via HCN, and HOCN, combining with ammonia and a number of other compounds.
In other words, you will be surprised to hear, but electric discharge in an atmosphere of a variety of gases produces innumerable compounds. From this perspective, the formation of NO2 is not particularly surprising, if you get what I mean!
Don't you think this is cool? When I first heard about this, I thought, wow, how can anyone ever doubt evolution on a molecular level, where base chemicals are formed by discharge on primeval earth, which ultimately lead to the rise of complex systems such as the genetic code/translation to amion acids etc?

Sorry if this is slightly off topic, but couldnt help to contribute this, me being an aspiring biochemist :D

Making Jacob's Ladder

DarkVigilante - 20-10-2003 at 17:59

To make a good Jacob's ladder you need a high voltage source. I actually steal electrons from my TV to do this using aluminum foil but that method is like a capacitor and does not provide continuous arcs. Buy a high voltage transformer from Radio shack. (They use them for neon lights if I am not mistaken.) You can make your own, but I prefer to play it safe with stuff like that. No need to start fires if you can help it. Also, you don't really need to make a ladder. Just use a spark gap.

Actually building this thing...

DarkVigilante - 20-10-2003 at 18:26

Ok, there are a few complications here to consider. First, if you want to make any appreciable amount of HNO3, you need a way to replenish the N2/O2 for the mix without venting your NO2. Furthermore, as this reaction continues you will be losing pressure, so if you were planning to force the NO2 out through water you are going to have to devise a mechanism for this. You also want to be a little more clever than using a soda bottle upside down with a ladder running into it. You don't want to breath NO2 in because this particular "silo-gas" can asfixiate you. NO2 becomes HNO3 in the lungs leading to inflamation that causes water to flood in and prevent Oxygen exchange in your lung's capilaries. Once this happens you drown in your own fluid? Catch my drift. Also, the guy up there makes a point. NO2 will be a product, but so will other chemicals. Still, I suspect that NO2 will be the most common product since N2 makes such a huge part of our atmosphere. Really, to make this system really effective you would need ways to control your mixture ratios. On the other hand, a bunch of dilute Nitric acid could be made and that might be concentrated easier. My advice for making this device is to use a vaccum flask with the metal ends of the spark gap running into a two holed stopper. The flask should be tall and water should fill the bottom so it can absorb the NO2 as it is produced. If you can find a one way pressure valve (like the ones they use on inflatable toys) you can attach that in a way allowing for new gases to come in as the pressure drops. (In lieu of that you can always use a clamped tube.) Still, don't forget that you also have other chemicals in this mix. You may want to occassionally stop the process and throughly vent the flask so that other chemicals don't build up and cause problems. Having never done this, I can't say for sure. Still, this idea is interesting and it would be cool to hear if anybody gets it to work.

BASF - 21-10-2003 at 04:38


will explain: they are basically two metal rods arranged in a "V" shape, and connected to a high-voltage source such as an oil burner transformer. When powered, an arc will start at the bottom and work its way to the top, then start at the bottom again and repeat this perhaps 2 or 3 times per second. If you've seen the original Frankenstein movie, you know what I'm talking about.

Why the V-design ?!!!!!

This is a nice thing for kids and films, but in terms of effectiveness it´s completely useless.

It is wrong to believe high voltage devices(especially from the kind you proposed) are needed.

It is the strenght of current that is crucial for the success in this process.

If you just have a spark, you can make a victory-dance, but the energy in such a spark is just too low.
You need a plasma for this reaction.

Just use a "Schweiss-Trafo" and everything will be fine :))

/chemoleo: any spark generates a little bit of O3, (nearly) no NO2(unless it is a high-current-spark).
Discover the basics behind transformers first;) and you´ll understand.

I believe the results of the experiment initially referred to are overestimated.

You need current strenght, not high voltages, and a plasma. - This allows using low voltage.

But you can use high voltage to ignite the plasma through which the low-voltage-high-current is able to pass.

Which electrodes?

Platinum, graphite.... it vapourizes, so it is necessary to adjust the electrodes from time to time.

[Edited on 21-10-2003 by BASF]

[Edited on 21-10-2003 by BASF]

Backyard Blaster - 21-10-2003 at 05:52

Yes, I'm now aware that the current is the main factor to consider. Oil burner, neon sign, or microwave oven transformers, seem best suited for this purpose. You're also right that the "V" shape isn't necessary; I was just pointing this out to describe what a real Jacobs ladder actually looks like.

chemoleo - 21-10-2003 at 11:46

/BASF I appreciate there are conditions where more, or less NO2, or O3 is produced. I never made a comment about efficiencies, or amounts. I am fully aware of the basics of transformers, but admittedly not so much about specific reactions going on in a high or low V/A spark environment. pz :D
Would you like to elaborate why a low V / high A spark between graphite electrodes (produced by a welding transformer = Schweiss Trafo) has a much greater yield of NO2?

Backyard Blaster - 21-10-2003 at 14:55

Correct me if I'm wrong, but - assuming by graphite electrodes you mean PbO2 - it seems to me that temperature would be a concern. Lead has a rather low melting point, and the arc temperature can be in the thousands of degrees celcius. Even a small HV arc can melt glass, for example.

Marvin - 22-10-2003 at 10:39

Correct me if I'm wrong, but assuming by graphite you mean a small albino elephant.

No, he means the carbon allotrope ;)

Carbon and tungston electrodes will not do very well, becuase allthough they have a high melting point, they both burn in air. Copper works acceptably if kept cool, this is only really a problem if you are putting in more than 100watts or so.

High current is not the issue, plasma is not the issue. All we are actually trying to do is raise the temperature of some mixed N2/O2 gas (usually air) to around 3000C, and then cool to around 1000C *very* fast. Thats it. Everything else is subserviant to this. Power into the air in the arc system is virtually all that matters.

When you have NO2, which forms after the gas is cooled to neer RT, you have to work out how you want to make nitric acid. Just with bubbling through a series of water bottles, or methods that concentrate the NO2 first (if you want >50%ish without sulphuric distilling). Either way, youd be building a mini factory.

V shaped design will work better than a static gap, but for decent performance, it needs to be aranged so the arc doesnt break at the top. The reason for this is that when the spark occurs, it forms an arc much too short to load match the transformer that creates it. By letting the ladder pull it almost to breaking point, you end up with an arc that matches the transformer much better. This means more power is dissupated heating the air, and less heating the transformer.

Most commercial designs include a virtical magnetic field to spread the arc out (actually zigzaging) though the air, which improvies the speed it can be heated and cooled.

Electrical welding machines are designed to dump as much as possible of the energy into the electrodes - not the air. Unsurprising, thats what welding is about. A design based on a welder is not likley to work well, and I can forsee a lot of problems with the arc chamber design.

NO2 is not mearly an asphixiating gas. Its highly toxic. Avoid breathing this stuff at all costs.

V-shape may have some value.

DarkVigilante - 22-10-2003 at 16:09

At first I thought the V-shape would be frivolous as well, but actually a simple spark gap may not expose as much air as the v-shape and since you do need some cool down time, allowing the arc to rise would allow for this sort of thing. As to current vs. voltage. You need higher voltage to jump a gap, I forget how much voltage is needed to jump a centimeter, but it is a lot. At least 1000 volts... As to current, this is more important in solution electrolysis then here. Remember, the orginal experiment was a Boyle's ladder and needed high voltage. Unless the guy who made this had really fancy equipment, we know he definately had high voltage but probably very low current. In electrolysis I would agree that current is far more the issue, but to have high voltages & high currents you risk endangering yourself while paying far more. I think one of us should actually build this thing and then maybe we can play around and see who is right.

everything ols is new

leopard - 22-10-2003 at 16:49

Yes this method of NO2 production works, as witnessed by the large facility operated at Niagara Falls about 1900. I have tested this method successfully.
1) Regarding the arc power is important as the hotter the arc the more efficient the conversion of N & O2 to NO2.
2) The longer the spark gap the more air is exposed to the high heat of the arc yielding more NO2.
3) 10,000 volts is a good and practical voltage as it will easilly strike an arc of 1cm. Current of 0.02 to 0.12 amps is also good and practical as it provides a good hot arc without being so hot that the electrodes are quickly melted.
4) Sealled air containers (glass jars) connected in series for air flow is desirable as tests show that traces of NO2 in the air increase conversion efficiency. The result is that there will be no noticeable colouration of the air in the first jar but the second etc. become progressively more brown with the increasing NO2 content.
In practice I used 2 glass jars of about 1 litre capacity each. I drilled 2 small holes near the bottom of each jar and inserted steel wire electrodes into the holes and sealled them with epoxy. I drilled 2 holes in each jar lid and soldered 5mm brass tubing into each hole. I connected a small electric air pump to the inlet of jar 1, connected the outlet of jar 1 to the inlet of jar 2 and the outlet of jar 2 was bubbled through water in a seperate jar. I used 2 neon transformers of 10,000 volts at 0.060 amps each to power the 2 spark gaps. I continuously pumped a low volume of fresh air through the system as it ran. Within about 20 hours of running time I produced about 50ml of HNO3 of unknown concentration but this acid yeilded about 1 large spoonfull of Urea Nitrate of good quality. The cost of electricity for production was very little.
By the way the air in jar 2 was very noticeably reddish/brown. I strongly feel that a clever person can easilly construct a very excellent NO2 generator that will run unmanned day in and day out for pennies.


DarkVigilante - 22-10-2003 at 17:03

Hmm, I can understand that running jars in series will make more NO2 but I wonder if more NO2 really helps more NO2 get made. That goes against equillibrium laws. Still, with such a large amount of electrictity running through that system and constant air running through its no issue really. Glad it works, I am going to build one myself. Now if only making H2SO4 was as easy...

BASF - 23-10-2003 at 00:48

I suppose the Birkeland-Eyde process uses a magnetic field on two sides of the reaction container to make an oval spark, this is definitely more sophisticated than the V-design.

/Marvin: maybe you are meaning that welding transformers provide a too low voltage to generate the needed oval spark?

BTW: i was reading that one of the reasons the Birkeland-Eyde-process was considered inferior by the Haber-Research group, was because the size of the spark simply could not be scaled up sufficiently to make it more economical. On the lab-scale it was reported to work very well, and could have been more successful than the catalytic ammonia-oxidation for some time, at least.


Congrats. I think the yield is rather bad for such a long time of reaction, but its on the other hand nice to see that recognizable amounts of NO can be generated.

It seems that welding trafos just have a too low voltage, although tremendous current strength. What about a second circle of current that provides the high voltage. Then the low-voltage/high-ampere current could flow through the shock-ionized air from the high voltage-spark. :P

[Edited on 23-10-2003 by BASF]

[Edited on 23-10-2003 by BASF]

DarkVigilante - 23-10-2003 at 20:33

Just screw the high current. When I did my test, I made 300 mL of 1 molar HNO3 after about an hour of operation. <5mV at about 100,000 volts was all it took. Look up "Van De Graf" generators to learn how this is possible.

dragora - 15-11-2003 at 01:03

i know no2 in ome made hno3 is very dangerous, how can be no2 be eliminated from home made hno3 ?

Mumbles - 15-11-2003 at 06:17

Do you mean in the production or in the final product.

In production, at least this method, it cannot. If you're distilling it, it can be greatly reduced thogh, by using a vacuum source.

In the final product you can bubble air through it to clear the nitric up. The addition of a small amount urea speeds up the removal of the NO<sub>2</sub>.

Nevermore - 15-11-2003 at 07:43

Originally posted by Backyard Blaster
Yes, I'm now aware that the current is the main factor to consider. Oil burner, neon sign, or microwave oven transformers, seem best suited for this purpose. You're also right that the "V" shape isn't necessary; I was just pointing this out to describe what a real Jacobs ladder actually looks like.

Well you talk about completely different items: microwave transformers usually give out no more than 2500V but at an incredible current, while on the opposite oil burner give much higher voltage up to 10000 with ridiculous the middle stays the NST, with 100mA for 10KV usually...(but there are many different, i have an 8KV 50mA).
I suppose or having higher tension is requested to go on more efficient conversion..van der graaf doesn't give out a continuous flow of current, neither the current is enough..i suggest the use of a tesla coil--1MV capable

Microtek - 15-11-2003 at 10:14

As a means of generating fuming HNO3, you guys might consider electrolysis of N2O4 in concentrated HNO3. N2O4 is oxidized to N2O5 and N2O4 is of course obtained by cooling the HNO3 with dissolved NO2.
Then, when the NO2 had been consumed, water could be added to convert the N2O5 to HNO3 and more NO2 could be pumped in. Perhaps you could even make a continous production....

unionised - 16-11-2003 at 14:13

What happens at the other electrode?

axehandle - 8-1-2004 at 15:43

This is very very interesting! Also I have
seen the very convincing picture with
the NO2 filled flask with the electrodes.

As it happens, I *have* a 40kV ignition coil
based HV generator using a 100W lighbulb
as a resistor together with a diode and a circuit i nicked from someones homepage (uses adjustable pulse-width-modulation with a huge transistor (driving the coil) and a 555-timer circuit + some more components. Whoever came up with the air-in-but-not-out idea using part of an inflatable toy (no, not that kind, perverts) deserves my alternative Nobel prize. I'll contruct the apparatus within the next few days and let you all know how it worked (if you don't hear from me, I'm probably just dead from NO2 poisoning =).

Btw, although my HV generator gives a very high voltage (depending on input, ca 40kV
using 12V), its current output is abysmal.

I've searched in vain for a CHEAP OBIT,
but have come up short. Anyone who knows
of a cheap source in case I succeed and want to increase my yield?

(I'm so excited at the prospect of making nitric out of thin air that I'm almost drooling. Better not ignore the ventilation due to excessive fixation...)

Nitric acid

Lestat - 1-5-2004 at 01:04

Well you could use the reaction between ammonium nitrogen triiodide (damp of course...), and concentrated silver nitrate solution. It would be expensive of course, but would yield concentrated nitric acid and an unstable explosive powder known as Szuhay's salt. Kills two birds with one stone so to speak.

Nitric acid with electric arc

kazaa81 - 1-5-2004 at 12:54

I've read in a U.S. Patent how producing nitric acid with an electric arc.

U.S. Patent 4,141,715

In the attachment there is a .zip file with the .tiff images of this patent

Attachment: U.S. Patent 4,141, (489kB)
This file has been downloaded 737 times

No file

Lestat - 1-5-2004 at 17:24

You appear to have actually included the files within the .zip lol, easily done, but I could really do with a synth for HNO3 that don't involve either expensive silver compounds or anything likely to remove bodyparts...

Watch your attitude mister

vulture - 2-5-2004 at 07:15


You appear to have actually included the files within the .zip lol, easily done, but I could really do with a synth for HNO3 that don't involve either expensive silver compounds or anything likely to remove bodyparts...

So your synthesis from NI3 should be considered safe then???

Lestat - 2-5-2004 at 09:27

Point taken Vulture.
I have to say that I have given up this method of HNO3 production, for exactly that reason. (decided to quite while I had ahead...)

Ps. No bad attitude intended Kazaa81, just leting you know that the zip file was blank.

[Edited on 2-5-2004 by Lestat]

agorot - 3-2-2010 at 14:46

[Edited on 4-2-2010 by agorot]