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darkflame89
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Yup, using graphite electrodes, stick them into the acid, connect to battery and water will leave the system as hydrogen gas and oxygen gas. Keep the
entire setup under low humidity, you wouldn't want the acid to suck water form air do you? 
I study this in my chemistry lessons, so i am quite sure of this.
Ignis ubique latet, naturam amplectitur omnem.
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frogfot
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Someone was talking about burning S to get SO2? How would one solve the problem with evaporating S? I mean, making some "afterburner" is not
an option for an amateur..
Wouldn't "lead chamber process" (KNO3+S) give same problem?
It seems that using NO2 as oxygen transporter for SO2-->SO3 is promicing. Just letting SO2/air/little ammount of NOx go through a long pipe.. This
would be sure simpler than heating a catalyst to do the same job...
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sanity gone
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what about single replacement?
I was thinking it might be possible to replace a sulpahate compound with single replacement and filter out the metal and what not.
[Edited on 14-5-2004 by sanity gone]
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axehandle
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Tish tish.
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Someone was talking about burning S to get SO2? How would one solve the problem with evaporating S? I mean, making some "afterburner" is not
an option for an amateur..
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That depends on the amateur.
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frogfot
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Yeah, but welding is most probably required.. 
Btw, what about electrolysis of CuSO4  :
CuSO4 + H2O --> H2SO4 + Cu
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darkflame89
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Ya i considered the electrolysis of CuSO4 too. While it is feasible, i need to make the CuSO4 by electrolysis too as it is not sold here.
Frogfot's idea about the NOx gases are good, what heppens to the NOx anyway? You see, i am trying to build a crude version of the birkeland-eyde
reactor of the synthesis of NOx gases so that nitric acid can be made.
About the burning of S, i am still thinking how to go about it, for one, i have very little experience on such things, two, I am looking at how
axehandle's project go and so hoping to learn something.
Ignis ubique latet, naturam amplectitur omnem.
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axehandle
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Ya i considered the electrolysis of CuSO4 too. While it is feasible, i need to make the CuSO4 by electrolysis too as it is not sold here.
Frogfot's idea about the NOx gases
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All pottery suppliers should have it. It's a very common glaze colour.
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are good, what heppens to the NOx anyway? You see, i am trying to build a
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In H2SO4 production? Recycled in Gay-Lussac (or was it Glover?) towers. Google for "lead chamber process".
Basically, the NO2 acts as a catalyst like this:
SO2 + NO2 --> SO3 + NO
NO +1/2O2 --> NO2
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crude version of the birkeland-eyde reactor of the synthesis of NOx gases so that nitric acid can be made.
About the burning of S, i am still thinking how to go about it, for one, i have very little experience on such things, two, I am looking at how
axehandle's project go and so hoping to learn something.
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So am I, so am I. I think my new furnace will need about a week to dry out completely, then it's casting time. A week on hold is also good for my
hand to have a chance to heal -- and besides, casting aluminium while on morphine is probably a bad idea .
[Edited on 2004-5-14 by axehandle]
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frogfot
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Whow, that Birkeland-Eyde reactor thread is a nice read!
As for SO2 source, it would be really nice to get some Na2SO3 ...mmm, wish it was sold in usual stores.. Then one could "spice" it with
enough nitrite so that on addition on say HCl or battery H2SO4 one would get SO2 with known ammount of NOx. Smaller concentrations would basically
require a long "reaction pipe". (One thing I'm not sure about is, if it's ok to add a nitrite to Na2SO3 soln.. I mean if theres
any sidereactions)
Axehandle I have trouble to find a good airpump that does not make much noise.. Currently I use one of those car tier compressors (running at 9V
instead of 12V).. Though that thing is cheap, it's very loud.. 
I seen you're using aquarium pump, but doesn't those heat up alot?
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axehandle
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Axehandle I have trouble to find a good airpump that does not make much noise.. Currently I use one of those car tier compressors (running at 9V
instead of 12V).. Though that thing is cheap, it's very loud..
I seen you're using aquarium pump, but doesn't those heat up alot?
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Not that I've noticed. But I use the kind that are good down to a water depth of 2..3 meters, which is overkill for this application. They are
virtually silent. A bit too expensive as well, unfortunately. I've been thinking of constructing a cylinder-piston pump with a small electrical
motor, but I don't think I'll be able to without a lathe. The aquarium pumps at least work, and are silent.
Edit: 3 of those damned things cost me about 1200 SEK....
[Edited on 2004-5-14 by axehandle]
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frogfot
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Whow, 400kr (50$).. thats like price of a big garden pump..
Anyway, I have tryed to solve the noise problem by covering my pump with a 30l bucket. Noise is greately reduced, and there is enough of air to cool
the motor. Mine cost 13$ (huh and it can give like 18atm.. but thats another thing)
Duh, I wanna correct my last post..
I just found out that SO3 contacting with water is a "no no", since this'll form a fog that is very hard to settle down. Thats why
it's not adviseable to ubtain SO2 mix from aqueous Na2SO3/nitrite mix..
Better way would be to make all gases separately, dry them over CaCl2, and only then the SO2, NOx and air would be mixed and transported through a
long pipe (copper pipe would do here, or?)
Huh, I'm more and more interested in this synth..
Btw, in industry they use 98% H2SO4 to absorb SO3. Would 95% do? ..difference is not big, but I'm not experienced in this..
[Edited on 14-5-2004 by frogfot]
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axehandle
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Where did you get that pump? It sounds interesting if it can be "silenced".
Cu piping should be fine if it's dry air/SO2 mix, as far as I've been able to determine. It might get eaten trough in a year or something,
though.
I haven't really solved the catch-22 problem when it comes to the absorption yet. I am going to try direct contact between the water surface and
the generated SO3. It should stay put in the water as H2SO4 then, I'd _think_. Worst case: I'll take a small trip to Denmark and buy a liter
of H2SO4.
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frogfot
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Try www.jula.se or www.biltema.se (art. nr. 15-980), both sell same thing, but first store sell it cheaper.. (for some reason first adress doesn't work.. but it
will.. someday.. )
Thay got also small silent (58db) air compressor but it's more expencive..
As for absorbtion of SO3, I thoat to assemble my 25 cm long fractionating column that will have a dropping funnel with H2SO4.. All this will be in
glass, I basically got all equipement.. but that experiment is just in theory untill I find source of Na2SO3..
Wondering if theres an accurate way to calculate lead content in car battery acid? We basically got some dissolved PbSO4 and Pb(HSO4)2. The problem
with calculations is that solubility of the first salt decreases with cons of H2SO4, but it's the opposite for the second salt..
Wish there was an easier way to check Pb content (not using EDTA..)
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darkflame89
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I know that that SO3 gas in contact with water is a very bad idea, but how do you absorb it with sulphuric acid when you do not have any sulphuric
acid, and that is the purpose why i am going to such lengths to "manufacture acids" at home..
Ignis ubique latet, naturam amplectitur omnem.
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axehandle
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Good point
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I know that that SO3 gas in contact with water is a very bad idea, but how do you absorb it with sulphuric acid when you do not have any sulphuric
acid, and that is the purpose why i am going to such lengths to "manufacture acids" at home..
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That, mate, is my catch-22 situation. A lead-chember-like absorption thingie could probably be used during the first run, after that (when I have a
litre or two of H2SO4), I can use the industry standard: Let is absorb in 98% H2SO4, add water as needed during the process.
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frogfot
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Huh, I can boil down the battery acid to get approx. 95%, I've tested this already. But this procidure is a bit dangerous, so I wanna avoid it
totally (well, boiling H2SO4 is probably more dangerous than handling oleum)
Thats why I was asking couple of posts above if it's ok to use 95% instead of 98% in SO3 absorbtion..
Oh, I didn't know what was catch 22
Didn't lead chamber gave only up to 70%? maby I'm wrong..
EDIT: Oh, just wanned to point out that oleum can be only diluted with 50% H2SO4, I heard it exploded on contact with just water..
[Edited on 15-5-2004 by frogfot]
[Edited on 15-5-2004 by frogfot]
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S.C. Wack
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some different tacks
A pair of Swiss chemists were granted a pair of interesting patents: GB618548 and US2531137. Usually when one thinks HCl, NaCl, H2SO4, the HCl is
being produced. In the GB patent this runs backwards: Na2SO4 + HCl = NaCl + H2SO4. The US patent is Cl2 + SO2 + Na2SO4 + H2O = 2H2SO4 + NaCl. The
first reaction is practical if it works. I would not be posting patents that required pressure, vacuum, etc.
As for the ferrous sulfate, oxidation to ferric is not a problem, according to Mellor. He says that heating FeSO4.H2O proceeds through the ferric
intermediate.The very first prep mentioned of SO3 by him is: Fe2(SO4)3 + distill = Fe2O3 + 3SO3. He also illustrates a nifty apparatus for lab prep of
SO3 or H2SO4 from SO2/air. He says that the yields using Fe2O3(instead of V2O5 or Pt) as catalyst are 60%.
The CRC gives the "temperature of energetic decomposition" to SO3:
PbSO4 - 705
CuSO4 - 670
This may still take a long time though. This may be a way around the crap that is in the "93% H2SO4" of the hardware stores, if the salts
you make from it can be crystallized nicely.
I've seen patents that state that when ammonium sulfate is heated in H2SO4, ammonium bisulfate and and NH3 are released. However, WO03027018,
says that if ammonium sulfate and H2SO4 are heated to pretty much exactly 280C, ammonia and more sulfuric acid are the products. If the bisulfate is
the actual or by-product, he does not say so.
Patents are often wrong or misleading, and espacenet itself is unreliable. One day it will tell you there is no such patent, the next day it will show
the patent, and the next day you may be unable to access the site at all.
Mentioned before but worth repeating: 2NaHSO4 + 400C = Na2S2O7. Na2S2O7 + H2SO4 + heat = 2NaHSO4 + SO3. This could be a way around crap H2SO4,
converting it to SO3. No, SO3 does not explode on contact with water. Hot, loud, fuming, yes, explosive no.
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BromicAcid
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Now i am collecting every single form of making sulphuric acid
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This just crossed my mind today although I have never done this so it is just specualtion.
CuSO4 (aq) + HCCH (g) ----> H2SO4 (aq) + CuC2 (s)
Being that copper acetylide is somewhat insoluble. However I don't know how readily it forms or how well it deals with concentrated acid or even
how available copper sulfate is in countries where sulfuric acid is commercially unavalible. However copper sulfate is avalible here and MAPP gas is
too, which contains a decent % of C2H2 but it doesn't matter as H2SO4 is OTC here.
Edit: Yes I knew copper acetylide was explosive but that is what made this method so mad, however it appears from my initial searching that this
compound only forms in the presence of ammonia or under basic conditions, in either of those two circumstances any H2SO4 formed would be immediately
consumed and therefore this method now appears to be a flop (I tried, oh
well...)
[Edited on 5/26/2004 by BromicAcid]
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sanity gone
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CuSO4 production
The way I got my CuSO4 was by the electrolysis of MgSO4 (commonly sold as Epsom Salts) with copper electrodes. What I did was make a highly saturated
solution and used the temprature method to crystalize CuSO4. If I find time I'll go down to the lab and try this.
Note: The electrolysis of MgSO4 also makes really dilute H2SO4.
Also, if you want elemental sulfur I think it is done by:
Na2S + KIO3-->S + I- + KOH, but I'm not 100% sure.
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darkflame89
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I know, i know, i have done that before. Regarding the production of sulfur, that's a little tricky, there is generally no such sources of
sulfide
Ignis ubique latet, naturam amplectitur omnem.
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sanity gone
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new idea for sulfur
I was doing some research and thought I'd pass a different idea along:
Fools Gold (pyrite) is FeS. An old method for sulfuric acid production was roasting pyrite (I think it happens around 150C).
4 FeS + 7 O2--> 2 Fe2O3 + 4 SO2(g)
2SO2+O2-->2SO3
SO3+H20--->H2SO4
So, in theroy... 20g of pyrite could yeild 4.55M H2SO4 in 50mL of H2O (I think my math holds up, but haven't double checked).
[Edited on 29-5-2004 by sanity gone]
[Edited on 30-5-2004 by sanity gone]
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darkflame89
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Ah..good idea there, but I don't think there's pyrite round here in Singapore. But I will scoot around and see. Also, you can add
hydrochloric acid to the sulfide, and hydrogen sulfide gas will be given off..
Ignis ubique latet, naturam amplectitur omnem.
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Chemtastic
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I used to collect rocks, and I bought a sample of sulfur (I'd say about a mole of it) for $3. It seems reasonably pure, and if it has any
contaminants, I would think only the sulfur could be readily oxidized by atmospheric O2.
So, S + O2 --> SO2
And SO3 + H2O --> H2SO4.
Wouldn't the most convenient method be to find a reaction for the conversion of sulfur dioxide to sulfur trioxide?
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Theoretic
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Nitrite and sulfite in aqueous solution don't give side reactions, they give hydroxylammonium derivatives in full yield, that are then hydrolysed
to hydroxylamine...
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chemoleo
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sanity gone/chemtastic -
pyrite is FeS2 to my knowledge. It doesn't react with HCl, while FeS does (producing H2S, smelly).
Nonetheless... if you read around the forum a little bit, you will find that SO2 oxidation is not quite as simple as it sounds- I suggest you read
some of axehandles threads. It requires high temps, catalyst, and a decent flow of SO2. Other than doing the FeS2 roasting on an industrial scale, I
don't see much chance on doing it at home!
Never Stop to Begin, and Never Begin to Stop...
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sanity gone
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Well I *think* FeS<sub>2</sub> can be oxidized by the reaction of:
4FeS2 + 15O2 + 14H2O --> 4Fe(OH)3 + 8H2SO4
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