Electrolysis of Ammonia

[YayItGoBoom!]

This has been a burning question of mine for a while, and I don't have the balls to ask it on the other forums (still a noob), so the water cooler seems like the best place. For production of NOx, I was thinking you could run a high voltage electrical arc through hydrated ammonia, with sufficient oxygen. I have not seen any other posts talking about this (I've read just about everything in the Nitric section), and numerous searches have brought up nothing. This leads me to the conclusion that 1) it forms diatomic hydrogen + electrical spark :eek: 2) it doesn't do crap, which would make sense because nitrogen compounds are not that stable, then again running an arc through air can produce NOx. I've been trying to make a device that I could test this with made out of snapple bottles but it keeps breaking the glass when I try to drill the electrode holes! But has anyone tried this, and how well has it worked?

[xyz]

You can make NOx by simply passing a high voltage/current arc through air.

So long as your equipment is kept dry then you can use plastic up until the point where the NOx is bubbled throguh water to make nitric.

EDIT: Oops, looks like you already knew that air could be used, yes this method has been tried by a couple of members but I can't remember who it was (10fingers?), and he was able to produce 500mL of nitric in a few days.

IIRC I think he used a microwave oven transformer to get the voltage/current required.

[YayItGoBoom!]

Yea I guess I was thinking along the lines of electrical arc-driven Ostwald process, minus the platinum (still can't find a cat converter grrr), but then I realized air has 70% N (smacks self), once I get a TV transformer I will try a Jacob's ladder setup, though there was a microwave on the side of the road with some other "For Free" stuff, my mom wouldn't pull over though (realizes the need for own car once again).

On a side note, I have about 100-200 grams of Ammonium Chloride, used for moisture absorbers I presume. I read about Silica gel being able to absorb and catalyze NOx and later release it, would NH4Cl have a similar effect, perhaps form NH4NO3 and Cl2 gas (yummy, jk).

Wait, wouldn't it form NH4NO3 if you bubbled NOx into Ammonia? The water would absorb and form some HNO3 and that would probably react with the NH4OH. If it works, it would result in less loss of NOx I think which is good becomes it comes at a price (not really I don't pay utilities yay).

[xyz]

Yes it would form NH4NO3 if you bubbled it through ammonia, but HNO3 is much more useful and can be turned into NH4NO3 at a later date.

[Hang-Man]

Woulddn't just burning ammonia yeild NO2? as in 4NH3+7O2-->4NO2+6H2O? maby I'm just an idiot.

[YayItGoBoom!]

I don't think hydrous ammonia burns, it has too high of a water content, and the rest is a stable salt (NH4OH). Maybe if you added a chemical you might be able to get it to burn, meaning Period 1 elements...That would just give off ammonia gas though -

NH4OH + Na ---> NaOH + H+ + NH3
I believe the hydrogen ion would be absorbed by the water or precipitate as hydrogen gas. Well it still doesn't solve the problem that I've been facing all along - Nitric Acid. Grrr...Right now it still seems like an air spark is the best way to produce NOx (goes and thinks on the crapper for a while)

BTW this is a problem for me because I have pretty much no way to get my hands on any kind of oxidizing chemicals. Fireworks are illegal in NY, I don't have a car to drive around looking for fertilizer and then there is still no guarntee that I will find any. If only it were 50 years ago....yea thats what we all wish.

[Hang-Man]

YayYouGoBoom if you try to tell me what I can and can't burn. If something has "too high a water content" what will happen if I heat it up? Will the water evaporate? I think so. Will it dehydrate? I think it will. Anything will burn if you get it hot enough, more so if it is entirely composed of hydrogen and nitrogen. And if you can’t find "oxidizing chemicals" in NY I pity you.

[nitric63]

If you heat aqueous ammonia the ammonia gas will be released along with water vapors so it
will still have high water content unless the NH4OH was very concentrated to start with. You'll
need an ammonia generator that uses an ammonium salt and a hydroxide like NaOH along with
a dessicating chamber to get anhydrous NH3 easily. Then you could oxidize it. Also, everything
most certainly will not burn if you get it hot enough, ever hear of the noble gases?

[Zeitgeist]

Actually didn't they use anhydrous NH3 as a fuel for the X-51? With liquid Oxygen as a rocket propellant in other things too IIRC.

Maybe you get N2 if it burns with insufficent oxygen

[YayItGoBoom!]

Yes I know you can burn just about everything, its called fluorine (XeOF6, used in microchip etching I believe). We're talking some kid's basement here. And it wouldn't be so hard to get nitrogenous compounds if I had a car, which I don't, so I'm stuck here pondering up the possibilies of nitrogen oxidation. Though I think I have come up with something that could produce a decent amount of nitric acid and other useful nitrates. A high power electrical arc (thinking carbon arc lamp) is used to produce Ozone, as well as NOx. This air mix is supplied with auxillary oxygen and bubbled through the ammonia. The ozone oxidizes the nitrogen of ammonia, leaving water and hydrogen gas, while the NOx readily converts NH4NO3. It seems a lot more efficent than using a spark to produce NOx and bubbling it through water, making very little use of the extra ozone.

[Sonny Jim]

I tried to generate a high voltage arc today by using a step down transformer backwards. I don't know if it would work at all since it blew out the power every time I tried to turn it on. Is there a good way to prevent this from happening?

[xyz]

Hook something into the circuit to provide resistance (such as a resistor, a heater, some lightbulbs, etc.) this will lower the amount of current passing through the circuit and it won't cause problems any more.

I advise that you get a multimeter, and learn about Ohm's law. If you do these two things you will be able to work out exactly how much resistance you need for the best balance between arc power and not causing problems.

[T_Pyro]

A step-down transformer generally uses thicker guage copper wire for the primary, and the secondary has narrower guage wire. If you try to use it in the reverse order, you'll be connecting the narrow guage coil (with lesser windings) to the power supply. With such a setup, you'll end up either blowing the mains fuse due to excessive current flowing through the primary coil (which was originally the secondary), or just end up vapourising your primary. If you try to limit the current in the primary coil by using a current limiting resistor, you'll end up reducing the power output of the secondary. Also, there'll be quite some wastage of power due to the resistor.
Why don't you just get a step-up transformer from an old TV or microwave?

[Sonny Jim]

I think I will do. I've gotten through so many DC converters though, by frying the diodes, I have a good few of said transformers lying about for experimentation. If they end up cooking, it serves them right for being part of an already broken devive :p

Ive been thinking as to whether there's actually any point in going into the high voltage region though. I reckon a good few spark plugs fixed along a PVC pipe could do a similar job, without having to go into dangerous levels of power, relatively speaking.

By the way, if you havn't guessed already, Im doing this to try and form NO2.

[Anthony]

What about a microwave oven transformer? Plentiful, high power handling, and relatively high current output, if ~2Kv is enough for you.

Surely on a step-down transformer, the secondary will have the thickest windings? As there's more current on the low voltage side, and due to the lower number of turns, there's more room for thicker wire.

[Sonny Jim]

I just have to get one of them. I've heard them mentioned as a good source of high voltages so often here!

A quick question though. How far will, say, from a microwave transformer, the electrical arcs jump? Ive had a long and interesting read on the thread in the HNO3 project section, but it doesnt say much about the arks themselves. Sorry if this is irritating but I've always been brought up to be scared of electricity, and it seems to have affected me more than I thought!

[Ollie Snowie]

I have seen pictures of the arcs from MOTs getting to 10cm in length. I have personally acheived ~5cm arcs, but that was with my heavy resistive load in series for current limitation. This is sure to decrease the voltage a bit and definitely the current (Well, that's what it's there for!).
Also, I've tried putting a H.V. arc through ammonia ages ago and definitely didn't get any NOx. Maybe it wasn't conc. enough or maybe it just won't happen.
From my experiments with electric arcs goung through air to make NOx I have found that it is best to have a power supply capable of very long arcs but keep the electrodes close together, play around with magnets to make the arc unstable in the position that it would normally be most stable in, and then suck air quickly through the arc and into a tube. The arc is stretched out by the air frow and the magnets and the residence time of the air is short, creating lots of air containing a smellable conc. of NOx in it. Also, if the arc does break, the electrodes are close enough together to form it again with no gap adjustment.

[EDIT - IMPORTANT - If you are getting one of these be careful to discharge the capacitor first with two electrodes on the ends of poles connected with a wire. The capacitors usually contain a bleed resistor to serve the same purpose, only slower, but just be on the safe side with capacitors that could cause a limb to explode.]

[T_Pyro]

Anthony:
The secondary windings should, and do use a thinner copper wire. Even if the current in the secondary is greater, the power dissipation in the primary will still turn out to be greater, unless the step-down ratio isn't too high. Both the secondary, and primary coils are wound over the same core in most real-world transformers, so the question of "more room" does not arise.

Like Ollie Snowie said, be sure to discharge the capacitor before touching any contacts. While discharging the capacitor, do NOT, I repeat, do NOT just short the terminals with a simple wire, or you'll get a major fireworks display. Use some current limiting resistor in series with a thick copper wire to discharge the capacitor gradually.

The distance that the spark can travel depends on the dielectric constant of the medium, and the dielectric strength of the medium. Reducing the pressure of the gases reduces the dielectric strength, thus increasing the probability of sparking. Also, if the air is ionised before entering the electric arc chamber, the arc can be made longer. For best results, try low pressure, pre-ionised air in the arc chamber.

[Tuatara]

T_Pyro: there are no hard and fast rules as to which side of a transformer has the thicker wire. In general the higher the current in a winding, the thicker the wire is. Usually the manufacturer designs the transformer to have equal loss in the primary and secondary to give best efficiency and use of materials. The big problems with just reversing an ordinary step-down transformer are
a) the insulation inside the transformer will not withstand the higher voltages
b) the magnetising current will be huge, as you are now driving way too much voltage into a small inductance. Most likely the transformer core will saturate and the inductance will drop to 1/100th, so the current skyrockets and the breakers trip.

For gas breakdown voltage under low pressure search the web for "Paschen's Law". The breakdown voltage of a gas is largely related to the mean free path length of the gas molecules. The breakdown voltage of dry air at sea level is about 3kV/mm, damp air seems to be around 1kV/mm.

In air you may notice that you can strike an arc at a certain distance , then draw it out further by spreading the terminals. Strike distance depends on voltage, how far you can stretch the arc depends largely on the current. The construction of the arc terminals also affects strike distance (pointy => further)

Useful hint: ordinary light bulbs make great resistors for discharging capacitors - when the light goes out the cap is discharged!

[T_Pyro]

Tuatara: You are right in stating that there are no hard and fast rules as to which side of a transformer has the thicker wire. However, for a 230V AC I/P, 12V DC O/P (the most common type I've come across) power adapter, the secondary is either designed for 1000mA, 12V O/P, or 35V, 2A O/P, which is then connected to a regulator (like the LM317). In such a transformer, the secondary coil, I've noticed, almost always has a thinner copper wire. Like you said, such a coil would have a very low inductance, causing the rms current value to exceed the rated value, and thus melting the leads/frame/insulation etc. I'd once tried to use a transformer in this way in our elecs lab, and ended up blowing the fuse, as well as melting the plastic frame of the transformer... Not a pretty sight!:eek:

I'm curious: How good are the yields in terms of purity/ quantity of products in this small-scale method of preparing nitric? I really don't have much of a problem getting hold of nitric acid, but if anybody recommends this process as a fair alternative to buying the acid, I might set up my own plant...

[Ollie Snowie]

I have to say that ordinary light bulbs will be a very bad choice for discharging this type of capacitor. Most likely the thin wire will explode from the intense heat and send bits of glass flying. You are alright with discharging one of these capacitors with a fairly thick (~1mm) copper wire connected between two insulating rods for handling. Microwave oven capacitors are not that huge (They will discharge through 1mm coper wire without a fireworks display apart from at the terminals, but you can be ready for that. The bleed resistor will probably have already discharged the capacitor - this is just for extra safety.).

Also, I see no point in using step-down transformers backwards. They will saturate, as Tutara said, and MOTs are readily available and just right for this purpose (Perhaps the current could do with being a bit lower and the voltage a bit higher.).

Also, before disaharging a capacitor with a short circuit, check that the capactior does not contain PCB oils - it normally says so if the capacitor is PCB free. PCBs are poisonous.

I think that a series resistor would definitely be a good idea as the capacitors sometimes explode from the intense magnetic repulsion between the plates in rolled capacitors when discharging them without a series resistor. The only problem is that normal resistors explode with high voltage capacitors as well.

You should be fine with rubber gloves for insulation and DRY, THICK woolen gloves for an air gap while holding the outside of the capacitor, but don't go prodding the terminals all the same.

[Tuatara]

You just have to pick your lightbulb ;)

Bleed resistors are an extremely good idea - a permanently affixed discharge device can avoid nasty accidents. For this application a 5W 1 MegOhm would do just fine. You can even put a little neon bulb in series with another 1 meg resistor, in parallel with the bleeder - if its glowing then theres at least 90V on the cap, and it will bite!

I did just this to the electric fence energiser that gave me the nasty 25 joule 900V shock. Never got bitten after that.

I've never personally had a cap explode through heavy discharge, but I have seen them go open circuit. It seems the high current gradually burns the connection between the foil and the lead wires. I opened about 10 of them that failed in my fence energiser, thats how I know. They only failed because the fuckwits who made them didn't understand I^2T ratings, and gave their caps too high a rating, which I used of course.