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blip
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Are you sure hydrogen would provide a safe inert atmosphere over the sodium? I've read that lithium reacts with hydrogen without any coaxing and
I'd think the same would happen with sodium.
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Organikum
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After five or more books on chemical engineering describe the the Na from NaOH process this way I see a small chance that it can be done this way.
Actually I see this the best way to do this if one wants to use electrochemistry.
Sorry - but I am a little pissed - what more than the original picture from a serious book and the correct translation does it take?
Look at the "Castner Tiegel"!
You will see in the middle above the cathode "Na". And above this "H2".
If the sodium would react with the hydrogen the whole fucking Na from NaOH would be complete impossible!
sorry.
I am pissed.
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rikkitikkitavi
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organikum, what books did you find this information in. I have been looking for info on electrolysis of NaOH,since it is much lower tempereatures
involved.
Can you scan the pages and put on the ftp (when it is up and running) ?
/rickard
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blip
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Sorry about that Organikum.  When I see that a thread has new posts, I usually
don't reread the entire thread.
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Theoretic
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So, you'd like a low melting point, huh...
Well, here's a candidate. NaHSO4, melting point 177C. No ceramic vessel corrosion -although I'm worried about metal, since the salt is
acidic.
Besides, I think the cathode product of the electrolysis would be H2S2O8 - perdisulfuric acid. Hydrolysis would yield H2O2, which is more volatile
than the H2SO4 also produced, so it could be distilled off.
Or, alternatively, H2S2O8 could be employed as a powerful (2.07V potential - acid) but not-so-fast oxidizing agent.
[Edited on 24-7-2003 by Theoretic]
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MaxPlanck
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NaHS04
I think this way you will simply get
lots of H2 and maybe S03 on the other
electrode. As you already said,
this salt is acidic, so it will attack
the Na and H2 will evolve.
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Theoretic
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Oh well, .
But what about tribasic sodium phosphate? It's m.p. is 73-77C, and it's not corrosive. The cathode product P2O5 would dissolve in the melt
to form polyphosphates, and from time to time one would add CALCINED soda, CO2 is given off - the phosphate is regenerated
(it's a sort of catalyst for electrolysis of, on end, soda).
Just then I thought about NaNO3 and NaNO2 - no, sodium would be reoxidized as soon as formed (but maybe not that fast - worth a try -  ). The same problem with NaOH. 
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Polverone
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no such problem with NaOH
I've heard that sodium may dissolve in NaOH, but I don't think it will reduce it. What sort of reaction were you picturing?
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MaxPlanck
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Na reduces NaOH
at about 25 deg.Cels over NaOH melting point Na2O is formed and H2 is produced.
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Marvin
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I dont think so, though information on the subject is somewhat clouded.
According to a book on the manufacture of sodium metal that Ive been quoting for several years now (paraphased),
Yeild of a castner cell drops from 80% at 5C above to 0 at 25C above the melting point because the solubility of sodium metal in the hydroxide becomes
so high the solution becomes a metaloid. This conducts electricity like a metal and electrolysis stops.
I did some searching today however and,
According to US patent number 2,202,270 however sodium metal and hydroxide start to react when there is hydride or hydrogen around at the melting
point of the hydroxide. It goes on to say this reaction is preperativly useful for the monoxide at about 450C provided the hydrogen be removed from
the cell to alow it to go to completion.
I'm still leaning strongly towards the metaloid explanation though I'm less sure than I was a week ago. Its also the more recent of the
sources so the writers of the book should have considered the monoxide reaction allready. Where does your information come from Max?
[Edited on 2-8-2003 by Marvin]
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Hermes_Trismegistus
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SODIUM
Hmmm!
listen guys, I had a thought. I am certain that our esteemed progenitors have given a great deal of "energia cogentis"
to the vexing issue of sodium production, while the organic chemists creed is to avoid ultra-high temperatures at all costs, perhaps we are
unneccesarily complicating the obvious here.
The DOWNS cell is an apparatus equaled in its sophistication only by its simplicity.
Using the NaCl version seems a little foolhardy and expensive until you factor in the ruggedness and ease of manufacure. And the common
availability of materials procurement.
If a clever guy was to enroll in a local community college metalworking course at night school, I am sure he could knock a fairly sizable one
off for only a couple hundred dollars that would serve him well for the rest of his life.
and the skills and techniques learned in the course would be invaluable in future endeavors
As for a heat source, Dave Gingery's "lil Bertha" sixty dollar electric crucible furnace that will easily top 2200 degC will
certainly be adequate, and last practically forever at the lower heat settings required for common salt electrolysis.
It is also about size of a five gallon bucket and has all sorts of uses.
Perhaps Cl gas is fairly reactive, but not unnaturaly dangerous as long as you were careful to use good, robust gas-tight fittings.
And I KNOW that your collective genius can come up with oodles of uses for the Cl that is evolved.....HMMMM?
Has anyone here looked at a site selling Lindsay's Books? Certainly worth a look
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Marvin
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Hermes, were you born with three necks or did that happen later?
I can see the aparent advantages to using NaCl, but NaOH is pretty cheap, widely available and melts much lower. It might cost a little more than
salt, but youd probably save that on power bills and the apaeratus would be much safer.
Cl might seem like an added bonus but having a cell that forces you to produce both at the same time is a practical disadvantage at home. Furthur
although Cl2 is fairly docile at RT, its almost certainly a different animal at 900C. Add to this that Na has a third of an atmosphere vapour
pressure at the melting point of sodium chloride and this is enough to worry me a lot.
I would think most metalworking classes would use brazes that melted below 900C.
I am still convinced that a slightly butchered all stainless steel pressure cooker with NaOH offers the best bet for home sodium production. Keeping
the current through the cell adjusted to maintain the caustic soda just above its melting point through nickel electrodes and with a nickel or iron
diaphram.
The system has a big advantage that insulation/heating is not critical so you can daisy chain cells together to obtain a working voltage better
matched to computer PSUs which will probably be providing the power for most peoples attempts. This would be very difficult with a furnace setup.
[Edited on 29-11-2003 by Marvin]
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Hermes_Trismegistus
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I bow to your obvious munificence
However, it mght be worthwhile to note that NaCl is liquid at only 804 deg C and that with the addition of CaCl (the common industrial process) the
temp drops to around 600 degC
as for using brass brazing rods to cobble together your apparatus...
HMMMM!!!!
I dunno about that Paco....
brazed seals are notoriously liable to suprise failures.....
Watch the Simpsons much?
Remember the BEER BARON episode?
Remember when Homer was rolling around on the lawn, engulfed in blue flames?
if I was going to rely on a brazed seal in such spectacular fashion I would make damn sur I drilled and tapped the joints first so as to ensure that
any failure wasn't what they call a
"CATASTROPHIC FAILURE"
and while I was at it I would change my name to "THE INCREDIBLE, AMAZING, DEATH-DEFYING HERMES" and sew myself a pair of black and yellow
tights and paint a crash helmet to match!
----------
truth be told, I am thinking that having chlorine in my system might be a bit safer than having H and O in it, at least if there was going to be an
accidental combination that overall pressure would decrease quickly, not that you would be decomposing at ambient temp anyway (for reasons you have
already stated)
edit---ambient Pressure not ambient T
------------
of course your probably right though!
[Edited on 1-12-2003 by Hermes_Trismegistus]
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Organikum
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MARVIN IS RIGHT
Any pot made of solid steel or iron works, the thicker the better. Put an insulation of concrete on the outside then some glasswool on the sides. Heat
up slowly.
Use a iron net as diaphragm or higher voltages and wider distances between anode/cathode.
Use NaOH.
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Hermes_Trismegistus
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CONCRETE!!
Well if you are going to do the deed, at least use a pourable refractory material.
Or, in a pinch, you could even use common brick mortar mixed 2 parts to 5 parts with Pearlite (common inert potting soil additive).
However, this mixture would calcine after a few uses(temp dependant), causing the insulation to lose cohesion and become brittle and flaky.
Whatever you choose to do, don't use a heat sink like concrete!
I mean c'mon man! Why not just add cooling fins!
-------
P.S.
I am also pretty durn sure that the perforated Fe screen is more of a necessity than a performance option!
[Edited on 29-11-2003 by Hermes_Trismegistus]
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BromicAcid
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I don't know if anyone else has seen this website but when I found it I knew it would be invaluble to this thread.
http://ras.material.tohoku.ac.jp/~molten/molten_eut_query1.php
It's the "Molten Salt Database -Eutectic Finder" you can type in NaCl and get dozens of eutectic mixtures, some as low as 50 C. FeCl3
and NaCl has an eutectic at 151 C, that's reasonable, KCl-NaCl-ZnSO4 (1:1:1) eutectic at 290 °C. You would have to look at the reduction
potentials to see what metal you would get but I see this as quite the way to look into other eutectic mixtures.
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I am a fish
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Unfortunately, both zinc and iron have higher reduction potentials than sodium, and so these eutectics wouldn't be suitable.
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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Theoretic
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"351 CO(NH2)2-NaCl 90-10 112 C"
This one should work. Although I don't understand, what does mol percent mean? In this case, 0.9 mols of urea and 0.1 mols of salt?
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BromicAcid
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Looking up more of the recent subject matter on electrolysis of molten salts to get sodium metal I'm finding that in almost every case the sodium
metal is the cathode, eg. they add sodium to the melt before hand and run the current though the sodium metal where it collects a alumina ring.
However, here is one patent that sounded kind of nice.
| Quote: |
91781n Electrolytic method of recoving an alkali metal from a molten salt of the metal. Kummer, Joseph T.; Weber, Neill (Ford Motor Co.) Ger.
1,783,137 (Cl. C 22d), 22 Aug 1974, US Appl. 507, 624, 22 Oct 1965; 4 pp. Division of Ger. 1,596,077 (See Fr. 1,491,674, CA 68: 92484r).
Molten alakali metal is electrolically sepd. into 1 arm of a U-tube device, the other arm of which contains the molten salt, the 2 arms being sepd. by
a solid electrolyte of cryst. structure of which contains essentially Al and O ions in its lattice. Thus, the 2 arms of a U-tube are sepd. by a sym.
positioned plug of Na B-albumin [12005-48-0] e.g., Na2O.11Al2O3. In 1 arm an eutectic mixt. of Nano3 and NaNO2 is held at 245 C and molten Na
[7440-23-5] is introduced into the other arm. Electrodes are inserted into the melts and connected to a source of d.c. whereupon Na+ passes through
the solid electrolyte.
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Just think it's neat that NaNO3 is used and such.
One more thing, about my earlier thought about electrolysis of Lithium Chloride in ethanol. It would be interesting that if lithium was produced that
it would immediately react with the ethanol to produce the alkoxide. At the anode chlorine would be produced which would react with the ethanol to
produce CH2ClCH2OH but it would be nice if there was some catlyst to produce CH3CH2Cl from chlorine and ethanol because then it could do a Willamson
Ether Synthesis with the alkoxide to produce Diethyl Ether and lithium chloride which would react back with the electrodes and basically serve as a
catlyst to make ether. Also, the HCl produced as a byproduct of the chlorination of ethanol would react with ethanol being that it's anhydrous
and make CH3CH2Cl and H2O so you would end up with all kinds of crazy stuff.
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Organikum
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hermes,
have you ever seen the picture on page ONE of this thread showing a Castner-Tiegel?
HOW CAN SOMEBODY MAKE SOMETHING SO EASY SO COMPLICATED??????
A Castner-Cell wont spill any Cl2 - thats one of the reasons I propagate its use.
Put the cell in a metal bucket if you have fears but be assured any molten NaOH will immediately get solid as it escapes the cell - the temperature
isnt so far above the melting point at all in the NaOH process - another reason I propagate this way.
I have to repair my famous "MEGAFLAMER" now so excuse me please......
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Hermes_Trismegistus
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Das Lernen ist difficult.The Geschmack meiner eigenen Schuhe ist schlecht. Mein Kiefer ist wund.
Do ya feel like posting some more about that Castner-Tiegel cell?......Organikum?
When I searched the net...the top two posts were you and the third was in German.
[Edited on 8-12-2003 by Hermes_Trismegistus]
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Organikum
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Polverone
| Quote: |
Orgy: your electrolytic cell may work marvelously, but does it glow with heat and belch burning hydrogen? Does it?! I thought not.
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In Europe iron doesnt glow at about 330°C. Of course hydrogen is produced and should be burned directly at the outlet of the bell - this is favorable
in special if heating is done with an open flame.
Hermes you nitpicking nervesaw: You dont need pure nickel for the electrode. You can use plain copper, or nickel plated on copper or nickel plated on
whatthefuckever, or even plain iron, you can even leave away the diaphragm and use the iron pot as electrode. Also your fingers may work - but I guess
only for a VERY short time - it for sure makes an EXITING experience.
OK. I dislike this but as everyone seems to want the recipe to enable retarded idiots to cause trouble:
- Take a soupcan and burn the paint/laque away with a propane torch. Clean it insides. Put some concrete around the sides - at least 3cm, reinforce
the concrete with some steelfabric/wire or similar. Put it on a hotplate/gasstove - on the gasstove put an steelnet between flame and can to prevent
holes being burned into the bottom. Fill halffull with dry NaOH fresh from the box. Heat it till the NaOH melts and regulate the temperature just to
hold it in liquid stage - dont overheat! Put one SS nail in the can and one coppernail. Connect them to a car-batterycharger or better to a
car-battery with charger attached. Over the coppernail you have to put a iron-bell with a little hole on top for the hydrogen to escape. Plug in
charger. Run. Unplug charger and stop heating. Your bell is full SODIUM now.
And thats more than close enough IMHO.
- Please dont ask whats the + and whats the - pole.
- Please dont ask how to determine the distance between the nails.
- Please dont ask how to determine if the Castner-Tiegel is actually working.
- Please dont ask how to make the bell.
- Please dont ask how to attach the electric cable to the coppernail.
As if you cannot answer this for your own you definitivly shouldnt even think on making sodium metal.
Regarding pictures - see my "I am back" thread
[Edited on 10-12-2003 by Organikum]
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Marvin
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Organikum,
Quick question, if the bell is electrically connected to the copper nail, as the description implies... What stops the sodium forming on the outside
of the bell closest to the other nail rather than on the copper nail?
I have no information on overpotentials for copper, iron, or sodium in molten sodium hydroxide or for that matter on the conductivity of molten
hydroxide but Id be worried that even if this is in the right direction that it wouldnt be enough to prevent problems.
I dont like the idea of using a car battery either, they can push a lot of current at 12v and its only power you have to replace with the charger
anyway even if this can be done after the experiment.
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Organikum
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marvin
CASTNER TIEGEL.
- the bell isnt connected.
- the power provides internal heating
- of course there should be an isolated iron lid covering the cell to avoid H2O sucked from the air.
- the battery works mostly as a capazitator equalizing the usually pulsed output from the charger.
- if I would answer your problem with the current, I would answer one of my "Dont ask" points, sorry.
[Edited on 11-12-2003 by Moonmonster]
[Edited on 11-12-2003 by Organikum]
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BromicAcid
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Hey! How's about the electrolysis of molten sodium cyanide!
2NaCN ----> 2Na + (CN)2
Supposedly it works but I really don't fancy the idea of working with cyanogen and I don't know much about the behavior of molten cyanide
salts. 563 C is'nt too attractive a melting point either. But would the cyanogen react back with the sodium metal? If not you could enclose
the whole apparatus and run the exit gas though a solution of sodium hydroxide to convert back just run the reaction till all electolyzeable material
is consumed and you might have a big jolly pot of sodium.
Back on the Castner process. I think that I will attempt to make said apparatus so I figured the best place to start would be some good electrodes so
I picked up some nickel-silver rods, turns out that is just a term used and the rods are like 65% copper and 12% zinc with the remainder being nickel
and molybdenum so just a warning to others that might be attracted by them, I don't think they will hold up to well. But they do sell titanium
rods and I have heard good things about its corrosion resistance to molten hydroxides. I found a nice picture of a Castner cell in a book at my library and made a photocopy, it details all the parts in a seperate paragraph
nicely although I liked the origional one on the first page better. I think that I might post a the picture of this one later though.
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