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Polverone
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the pyrosulfates
I've been chatting with axehandle a bit via U2U. Here's some information that others might benefit from too:
| Quote: | The pyrosulphates of the alkali metals are obtained most easily by heating the corresponding acid sulphates to 300-350 C:
2KHSO4 = K2S2O7 + H2O.
This dehydration, however, does not proceed to completion even under reduced pressure, and in order to obtain the pure salts it is preferable to allow
the finely divided anhydrous normal sulphate to interact with sulfur trioxide. ... When heated strongly, for instance above 450 C, the pyrosulphates
undergo decomposition into sulphur trioxide and the corresponding normal sulphate. The sodium salt, which melts at 400.9 C, exhibits appreciable
dissociation at about 460 C. In contact with moist air or water the pyrosulphates become converted into the corresponding acid sulphates:
K2S2O7 + H2O = 2KHSO4
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Friend (editor), A Text-book of Inorganic Chemistry
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axehandle
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So, NaHSO4x1H2O into paint can. Hole with cork and glass pipe into lid. Heat the little sucker in my propane furnace until no water is formed anymore,
continue heating when SO3 is produced, down into bubbler with water until reaction stops.
I have lots of empty paint cans, corks and glass pipes. I also have a determination. I will NOT yield to the stupid ban on acids this fucking
government has impelled on me. I SHALL have my sulfuric acid, I'll die trying!
Hmmm, btw, isn't SO3 a solid at room temp.?
[Edited on 2004-1-31 by axehandle]
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rikkitikkitavi
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Polverone, actually , Na2SO4 shows very little solubility in water/EtOH solutions up to 30-40 % water content.
I will see if I can find my copies of gmelin about the Na2SO-NaHSO4-H2SO4 /H2O/EtOH /pyrosulfates that I have somewhere. It is only in german though,
but I can scan it. Very informative.
There is a few patents regarding decomposing NH4HSO4 by EtOH/MeOH since this is easier obtainable , but there is probably old patents regarding NaHSO4
to, since this was a byproduct with little use in manufacturing high conc HNO3 in late 19th.
axehandle, forget any metal in contact with molten hydrogensulfates. It eats it up in notime, actually molten pyrosulfate/hydrogensulfate is used for
dissolving in chemical analysis.
[Edited on 31-1-2004 by rikkitikkitavi]
[Edited on 31-1-2004 by rikkitikkitavi]
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axehandle
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Thanks. You just saved me a furnace contaminated with NaHSO4.
I'm right now dry distilling anhydrous FeSO4,
using empty paint can with cork and copper
tubing. Seems to work, albeit slowly.
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Organikum
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ehem
axehandle? SO3? Cork? Uiiiiiiiiiii.........
Ceramics, clay, pottery!!!!!
Wasserglas.....
Flowerpot and kruzifix nochamal!
Herrgottdaskannsdochnichtgeben.......
 
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chemoleo
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Lol Organikum - at times of need you just have to use cork  - or paper plugs!
By the way, all he will have is a little carbon impurity
Are you bavarian?
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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axehandle
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Orkanikum: Kork bist entwas für die chemische reaktion ich habe lust für.
Unt ich brugt nicht wasserglass, ich brugt Duranglas.
Ein Reich, eine Folke. ein Fuhrer!
I'm for the 1st: Joking, and for the 2nd: I don't know German, althouch my girlfriends father is an immigrated German.....
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axehandle
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Organikum: I actually understood all of your post, learning German as I am. I choose to ignore it.
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Tacho
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I have found by experience that NaHSO4 can substitute H2SO4 in many reactions. Every now and then I use it instead of H2SO4 for simple experiments. I
have made ethyl bromide using it.
I first got interested in it when I read somewhere that you could do destructive distilation (with silica?) to obtain H2SO4 the same way you do with
Iron sulfate. Never tested this.
Very easy to get, any pool shop should have it.
Also, when heated with common salt, produces a very acid gas (test paper goes red very quickly) which has to be HCl.
Anhydrous NaHSO4 should produce anhydrous HCl.
[Edited on 4-2-2004 by Tacho]
[Edited on 4-2-2004 by Tacho]
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Polverone
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I've wondered recently if NaBr could be used the same way to produce HBr without any oxidation like you'd get with H2SO4. I do recall
reading in some ancient manual of industrial chemistry that KHSO4 or NaHSO4 could be heated with sodium formate to give formic acid, without the
oxidation that H2SO4 would cause.
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rikkitikkitavi
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HSO4 pKa 2
HCOOH Pka 3,75
thus the reaction
Na-Fo + NaHSO4 => HFo + Na2SO4 has a pk of 1,75 , i e shifted to the right
Since HFo is volatile, it can be evaporated easily , thus drives reaction towards completion.
NaHSO4 reacts with NaCl to produce HCl , but at high temperatures, the hydrosulfate needs to be molten.
/rickard
[Edited on 4-2-2004 by rikkitikkitavi]
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axehandle
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Now I've had it!
After filling a steel pipe with anhydrous FeSO4 and putting it in my propane furnace in a (futile) attempt to produce H2SO4 (through bubbling), with
the result being stinking down my entire flat with SO2 (there must have been a leak somewhere, or perhaps the FeSO4 didn't like 1600 C of
temperature and decomposed into FeO2 + SO2), I've decided to go the whole way and build myself a nice, old-fashioned lead chamber.
You heard me: A lead chamber!
The contact method is out, mostly due to the fact that sulfur poisons the platinum, and I can't find a catalyst that would work without extreme
temperatures and be very hard to apply to a suitable substrate.
Now, I'm going to to try to find an enormous quantity of lead sheet for my chamber. The damned thing will probably weigh half a tonne, but
I'll be damned if I let these setbacks stop me!!!
So, unless someone can suggest a very easy to prepare and use catalyst for the contact method, lead chamber it is. Who knows, it might even impress
girls. (-Whats that? -Oh, it's just my lead chamber)....
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Mumbles
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1600C? I can tell you your problem without a doubt. The SO3 decomposed to SO2 and O2. I think it decomposes around 400 or 500. if you can get it
right near the decomposition point of the Sulfate the SO3 could probably cool enough before it decomposed to a great extent.
I do assume by the bubbling method you mean into Sulfuric Acid. Into water could do more than fill your flat with SO2 fumes.
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axehandle
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My suspicions confirmed are, somewhat. Thanks.
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Polverone
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wait a second
1600 C?! No way! Your steel pipe would have been converted to an incadescent puddle of metal. How are you estimating the temperature achieved? Also, I
believe that mixing fine silica with your sulfate may help it to decompose in the fashion you desire, since I recall the addition of silica from
descriptions of old techniques for producing H2SO4 from ferrous sulfate.
[Edited on 2-6-2004 by Polverone]
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axehandle
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Estimated maximum of the furnace. The inside is lined with a special mixture of bentonite, perlite and cement, which make a very goog heat insulator.
The pipe had, however, a yellow glow, so I would estimate 1000C.
Sorry for the confusion.
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Organikum
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to fast
Using cork but cant stand a joke..... tz tz
No, seriously:
You heated the FeSO4 to fast and to high as it sounds, you have to give it some time to dehydrate first, the water doesnt jump out of the molecule at
a certain temperature! This takes a while. So heat it to above the dehydration temperature and hold it there for some hours - then power it up to
make the H2SO4 etc. At this point your setup should be completely enclosed - and really, water-glass aka sodium silicate is favorable for lining the
steeltube insides and for sealing - I dont tease you, I try to help.
Lead is used in high-power electricity cables shielding - the kind of buried cables. About 100gram/10cm. Contact your local industrial scrapyard for
this. It is a fuck to get it out but its the best source for lead I know.
But you might consider to try the FeSO4 decomposition again - outsides so possible - and slowly as advised. Lining the steel with the silicate is a
good idea - believe me, not without reason writes the MERCK that water-glass is used for lining vessels used for acid concentration.
If you wont trust me,
trust the MERCK.
But hey! I got one more:
Der Führer war ein armes Schwein, er hatte keinen Führerschein!
Chemoleo:
I? Barbarian? I? - eh, perhaps....
[Edited on 6-2-2004 by Organikum]
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axehandle
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>to fast
>Using cork but cant stand a joke..... tz tz
I know that, but it was the only sealing material I had at hand, and the pipe _was_ sticking about 15cm out of the furnace... for
tubing I used a soft-annealed copper pipe.
>No, seriously:
>You heated the FeSO4 to fast and to high >as it sounds, you have to give it some
>time to dehydrate first, the water doesnt
>jump out of the molecule at a certain
>temperature! This takes a while. So heat it >to above the dehydration temperature
>and hold it there for some hours - then
>power it up to make
I did. I put a generous amount in the kitchen oven and dried it at 300C for about 3 hours. Should have done the trick, it changed colour and the
density went down considerably. It was pure Hell to break up the lump and get them through the small cork-hole in the pipe though...
>the H2SO4 etc. At this point your setup
>should be completely enclosed - and
>really, water-glass aka sodium silicate is
>favorable for lining the steeltube insides
> and for sealing - I dont tease you, I try to
> help.
I know that, your tone doesn't suggest otherwise. But I'm not planning to dry distill FeSO4 ad nauseam, it was a one-time shot and I missed.
I won't do it again, my furnace basically has two settings: 1: Off, 2: Full blast (I've built the propane burner myself and it has a lowest
setting that is not low enough...).
>Lead is used in high-power electricity
>cables shielding - the kind of buried cables.
>About 100gram/10cm. Contact your local
>industrial scrapyard for this. It is a fuck to
>get it out but its the best source for lead I >know.
I know a better one: Used X-ray shield plates. About 1.5mm thick, 200mm wide and anywhere from a piece to 2 meters in length. My local scrapyard deals
alot in them They are basically for free, but heavy as lead to carry, pun intended.
>But you might consider to try the FeSO4
>decomposition again - outsides so possible
> - and slowly as advised. Lining the steel
>with the silicate is a good idea - believe
>me, not without reason writes the MERCK
>that water-glass is used for lining vessels
>used for acid concentration.
I won't try it again, I've contacted a jeweller about some platinum. Next time it's either contact method, or most likely,
lead-chamber.
I only really need a small amount of acid, to
make a small amount of nitric to make aqua regia to make a catalyst on a kieselguhr substrate, etcetera. Catch-22.
Do you perchance know why many texts quote that the maximum concentration attainable in a lead-chamber is 78%? Shouldn't it be possible to boil
the water off, or has it got asomething to do with SO2(aq)?
>If you wont trust me, trust the MERCK.
I trust you both.
>But hey! I got one more:
>Der Führer war ein armes Schwein, er
>hatte keinen Führerschein!
The Führer was a poor pig, he had no foreskin (direct translation (and I think the _correct_ word for foreskin is Führschein, nicht war?)).
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Organikum
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no
driver-license is the right translation....
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axehandle
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oops
Freudian slip, it seems...... heh
But I think it was close enough. What's the consolation prize?
[Edited on 2004-2-6 by axehandle]
There, just drilled a 10mm hole through my apartment balcony wall for an exhaust from a fume fan. I wonder if my landlord will notice? *shudder*
[Edited on 2004-2-6 by axehandle]
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Magpie
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surely you mean 100mm!
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axehandle
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No, 10mm is exactly what I meant. I was a bit unclear though, it's not really for a fume hood exhaust, just for a trickle of air + NO from my
almost-finished Birkeland-Eyde reactor. The air flow comes from two humongous aquarium pumps, but 10mm is more than enough.
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rikkitikkitavi
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axehandle., FeSO4 decomposes into SO2.
You need Fe2(SO4)3 whcih decomposes into SO2 and SO3 when heated, and at lower temperature so the SO3 doesnt decompose.
/rickard
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Friedrich Wöhler
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That's true, that pure FeSO4, when heated, give a mix of SO2 and SO3.
But: [Hofmann/Rüdorff: Anorganische Chemie]
Centuries ago, they let FeSO4 ("iron vitriol" with moisture oxidize by
air to an Iron(III)-hydroxide-sulfate Fe(OH)SO4.
This, when heated, gives that "fuming sulfuric acid":
2 Fe(OH)SO4 ===(heat)===> Fe2O3 + H2S2O7 (thus H2SO4 + SO3).
You really can get it by blowing air through an FeSO4-solution, this Fe(OH)SO4 is unsoluble, you can it filter and dry.
How easily to oxidize an FeSO4-solution is, you can see when you dilute pure FeSO4 in hot water and in few minutes in contact with air it will change
its color ang get cloudily because of Fe(III)- building.
Just I don't know that decomposition temperature but I can remember it was very low. (Even must not glow...)
Kein Schwanz ist so hart wie das Leben.
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fritz
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Instead of Pt you can use following catalysts for oxidation of SO2:
V2O5-catalyst:
pumice and V2O5 in the ratio of 2:1 are wetted with water. Dried in vacuum and heated 30mins at 120°C
OR:
To pumice NH4VO3-sln (saturated) is added as much as the pumice can absorb. You let dry and make it glow carefully.
best use at 400-500°C
reaction starts at about 200°C
Cr2O3-catalyst:
Cr2O3 is heated strongly and brought onto glass-wool.
OR:
(NH4)2Cr2O7 is heated carefully and added to glass-wool.
best use at 200-300°C
Fe2O3-catalyst:
saturated FeSO4-sln. is absorbed on pumice or pieces of brickstone. After drying
heat it to 800°C until no more white smoke appears.
OR:
Fe2O3 is brought on pumice or brickstone
best use at 500-600°C
Fe2O3/CuO/Cr2O3-catalyst:
a mixture of Fe2O3; Cr2O3 and CuO (ratio:???) is dried at 120°C and brought onto glass-wool.
CuO/Cr2O3-catalyst:
CuSO4 and CrCl3 solution (both saturated) is absorbed on pumice. heat to 800°C until no more white smoke appears.
best use at 300-400°C
hope this will help you.
My source suggests asbestos as absorbing material but this seems not to be a good idea...
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