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ave369
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I will now be building and testing my new Batparatus!
What is the Batparatus? It is a distilling setup for sulfuric acid. If it works, it will be the final solution to the question of Boiling the Bat and
obtaining concentrated sulfuric acid. Here is a picture:
Explaining the Batparatus. Before it is used, the Bat is boiled dovn in a common round-bottom flask, until the vhite mist and unpleasant couffing
appear. Zen zis raw acid is put in the Batparatus.
It consists of a retort, the upper part of vhich is insulated by an asbestos cord, and a Liebig condenser. Normally you vould not vant to allov
sulfuric acid vapors in a vater-cooled Liebig condenser, but ze nose of ze retort and ze antechamber of ze consenser form ze air-cooling span, ze
vapors cool down when going through it and are safe now for entering ze Liebig condenser. Zen zey condense. And the asbestos is to prevent refluxing
of acid. All my previous attempts to distill sulfuric acid ended in all refluxing and no distillation.
Forgive me my Ubervaldian accent, but nov I'm in a true mad-sciencey mood! Probably that depression swinged to mania.
[Edited on 3-12-2015 by ave369]
[Edited on 3-12-2015 by ave369]
Smells like ammonia....
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Detonationology
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This looks great in concept, and I have never had to concentrate sulfuric...however, boiling the final percentage of water is going to be nearly
impossible considering it's so hygroscopic, I doubt it could become much more concentrated that 70% by boiling alone. I may be wrong, but I believe
that I have heard that chromium trioxide can be used to dehydrate the acid further.
[Edited on 12-3-2015 by Detonationology]
“There are no differences but differences of degree between different degrees of difference and no difference.” ― William James
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ave369
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It stops at 70% when simply boiling down. This is what I call a raw acid. And this raw acid I put in a specifically made distilling apparatus.
The chromium trioxide thing is called Zintl-Karyakin distillation. A good thing to do, if you have pure CrO3 or a dichromate of something other than
ammonium. That damned ammonium! It reduces hexavalent chromium right when I boil it, and all I get is dirty, green mix of H2SO4, Cr2(SO4)3 and Cr2O3!
I even tried isolating pure CrO3 from ammonium dichromate, but some trace of that damn ammonium snooped into my flask and once again made it all
green!
[Edited on 3-12-2015 by ave369]
Smells like ammonia....
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hissingnoise
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~98% H2SO4 is obtained by the gradual heating of dilute acid to ~300°C!
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Deathunter88
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Heating to ~300°C will make 85% sulphuric acid at best. You need to actually distill it for it to reach the azeotrope of 98%.
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ave369
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Quote: Originally posted by Deathunter88  |
Heating to ~300°C will make 85% sulphuric acid at best. You need to actually distill it for it to reach the azeotrope of 98%.
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Well, that is exactly what I'm trying to do. Invented even a new type of distiller to pre-cool the sulfuric acid vapors and prevent thermal cracking
in the liebig!
Right now, the distiller is working, the distillate drops merrily, but it is so far mostly water. The asbesting of the retort helped very much, it
sped up the distillation and stopped the unwanted refluxing on the retort walls.
[Edited on 3-12-2015 by ave369]
Smells like ammonia....
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Deathunter88
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| Quote: Originally posted by ave369 | | Quote: Originally posted by Deathunter88 |
Heating to ~300°C will make 85% sulphuric acid at best. You need to actually distill it for it to reach the azeotrope of 98%.
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Well, that is exactly what I'm trying to do. Invented even a new type of distiller to pre-cool the sulfuric acid vapors and prevent thermal cracking
in the liebig!
Right now, the distiller is working, the distillate drops merrily, but it is so far mostly water. The asbesting of the retort helped very much, it
sped up the distillation and stopped the unwanted refluxing on the retort walls.
[Edited on 3-12-2015 by ave369] |
Why not skip the 2 steps of air cooling then water cooling with a single air condenser?
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ave369
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Ta-dam! I've tested the apparatus and it was a success: I've obtained several drops of 98% azeotropic sulfuric acid from it. But then, my stove
overheated and threatened to unsolder. You see, Rekord-1 isn't a good brand of heating mantle.
So far, I've got a consolation prize: a full still bottom of technical grade, murky but nevertheless azeotropic acid!
And a Liebig there is to deal with the Mist. You know that Mist? It emerges from the retort nose unscathed, when you inhale it you cough and it smells
like Hell. Liebig stops it right there in its tracks.
[Edited on 3-12-2015 by ave369]
Smells like ammonia....
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Magpie
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Good work! I don't need to do this as I can buy 96% acid, but I recognize the technical challenges you had to overcome.
In some synthesis I was doing drops of water were falling back into the hot H2SO4 due to refluxing - the reaction was violent and scary. Apparently
you have eliminated this with the insulation.
I'm surprised that the Liebig condenser has eliminated the mist of oleum/SO3. This can be very difficult to condense.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Mesa
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Wouldn't that be easier to eliminate with a scrap of tyvek and a splash head?
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hissingnoise
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| Quote: | | Heating to ~300°C will make 85% sulphuric acid at best. You need to actually distill it for it to reach the azeotrope of 98%. |
(sigh!)The H2SO4 azeotrope (constant boiling mixture), if it can be called that, appears just below its BP, at which temp. some
acid decomposition occurs to keep the water content @ ~2%!
Allowing the acid to cool outdoors or in moist air generally will, of course, lower the conc. slightly as water is absorbed fairly avidly below
100°C.
And simply distilling 85% acid will give 85% acid as distillate . . .
Distilling H2SO4 is useful only when non-volatile contaminents are present!
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Deathunter88
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| Quote: Originally posted by hissingnoise | | Quote: | | Heating to ~300°C will make 85% sulphuric acid at best. You need to actually distill it for it to reach the azeotrope of 98%. |
(sigh!)The H2SO4 azeotrope (constant boiling mixture), if it can be called that, appears just below its BP, at which temp. some
acid decomposition occurs to keep the water content @ ~2%!
Allowing the acid to cool outdoors or in moist air generally will, of course, lower the conc. slightly as water is absorbed fairly avidly below
100°C.
And simply distilling 85% acid will give 85% acid as distillate . . .
Distilling H2SO4 is useful only when non-volatile contaminents are present!
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That is not true, when I distill 500ml of 93% acid the first 50ml or so is just water with a small amount of acid, not enough to even dehydrate
tissue, but the concentration increases until the 98% begins to distill.
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Etaoin Shrdlu
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| Quote: Originally posted by Deathunter88 | | Quote: Originally posted by hissingnoise | | Quote: | | Heating to ~300°C will make 85% sulphuric acid at best. You need to actually distill it for it to reach the azeotrope of 98%. |
(sigh!)The H2SO4 azeotrope (constant boiling mixture), if it can be called that, appears just below its BP, at which temp. some
acid decomposition occurs to keep the water content @ ~2%!
Allowing the acid to cool outdoors or in moist air generally will, of course, lower the conc. slightly as water is absorbed fairly avidly below
100°C.
And simply distilling 85% acid will give 85% acid as distillate . . .
Distilling H2SO4 is useful only when non-volatile contaminents are present!
|
That is not true, when I distill 500ml of 93% acid the first 50ml or so is just water with a small amount of acid, not enough to even dehydrate
tissue, but the concentration increases until the 98% begins to distill. |
...that's because you're not distilling acid, just boiling more water off until you hit the ~98% azeotrope.
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Magpie
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Although not at boiling the vapor composition in equilibrium with 95.06% H2SO4 has the following partial pressures, p, according to Perry's
Chemical Engineers' Handbook, 4th ed:
Temp: 282°C (boiling temp is between 285 and 290°C)
pH2SO4 = 52.6mmHg
pH2O = 350.2mmHg
This indicates that the mole ratio H2SO4/H2O =52.6 /350.2
= 0.15
Which in turn means that the vapor is (0.15/1.15) x 100% = 13 mole% H2SO4 = 45wt% H2SO4.
The vapor contains H2SO4 during distillation all the way from a pot concentration of 93% to 98% H2SO4.
At a pot concentration of 98% H2SO4 the vapor will contain 98% H2SO4, as this is the azeotrope.
[Edited on 4-12-2015 by Magpie]
[Edited on 4-12-2015 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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Deathunter88
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| Quote: Originally posted by Etaoin Shrdlu | | Quote: Originally posted by Deathunter88 | | Quote: Originally posted by hissingnoise | | Quote: | | Heating to ~300°C will make 85% sulphuric acid at best. You need to actually distill it for it to reach the azeotrope of 98%. |
(sigh!)The H2SO4 azeotrope (constant boiling mixture), if it can be called that, appears just below its BP, at which temp. some
acid decomposition occurs to keep the water content @ ~2%!
Allowing the acid to cool outdoors or in moist air generally will, of course, lower the conc. slightly as water is absorbed fairly avidly below
100°C.
And simply distilling 85% acid will give 85% acid as distillate . . .
Distilling H2SO4 is useful only when non-volatile contaminents are present!
|
That is not true, when I distill 500ml of 93% acid the first 50ml or so is just water with a small amount of acid, not enough to even dehydrate
tissue, but the concentration increases until the 98% begins to distill. |
...that's because you're not distilling acid, just boiling more water off until you hit the ~98% azeotrope. |
Is that not what distilling is? The water has a lower boiling point so boils off with a small amount of acid leaving the bulk acid more and more
concentrated until it finally reaches the 98% azeotrope and distills over. Just like distilling say vodka to 95% ethanol the concentration of the
distillate rises until it reaches 95%.
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ave369
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Actually, when you distill vodka (or rather moonshine, vodka is made on giant fractionating columns), it's the other way round. The concentration of
ethanol in the pot lowers, until it's 1-2% (still bottoms). The concentration of ethanol in the distillate also lowers (the first batch, the pervach,
is the strongest, but the most contaminated with toxicants like methanol or acetone. Here in Russia only the men with balls bigger than their brains
drink pervach. Then goes the golden middle, which is ethanol with concentration gradually lowering from 70% to 40%. Below 40%, feints begin, they are
not potable, either.
With sulfuric acid it is all the same, only the light volatile that escapes is the dreck, and the heavy thing that stays in the pot is the desired
product.
[Edited on 4-12-2015 by ave369]
Smells like ammonia....
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Deathunter88
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| Quote: Originally posted by ave369 | Actually, when you distill vodka (or rather moonshine, vodka is made on giant fractionating columns), it's the other way round.
[Edited on 4-12-2015 by ave369] |
By vodka I meant 80% pure alcohol. I realise that it is the other way around but nonetheless distilling H2SO4 is still "Distilling" and not "Boiling
off some water".
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hissingnoise
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What that means is that you mean you're hopelessly confused by the simple act of distillation . . . ? 
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ave369
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Stop arguing. I managed to distill H2SO4 in all possible senses of the word. I got several drops of it before my heating device malfunctioned.
And that the rest of my 98% H2SO4 was from the still bottoms, doesn't change anything.
Also, by finally obtaining sulfuric acid of this strength, I gave freedom to my little inner kewl and performed the reactions "black snake" and making
manganese heptoxide (I incinerated a cigarette butt in the heptoxide).
Nevertheless, now I have the technology and think true distillation is overkill: if the glassware is clean and the boiling chips are, too, driving off
the last water from the Bat in the pot with this apparatus is the more economical option. 98% sulfuric is now finally an OTC preparation for me! So
many possibilities!
[Edited on 4-12-2015 by ave369]
Smells like ammonia....
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hissingnoise
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Performing a urine extraction mustn't be mistaken for argument . . .
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Bert
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Hi everyone.
Please keep posts civil and directed to the matter at hand, which is apparently processing sulfuric acid to remove excess water... Not vodka. Not
urine, (I can sympathize with the proponents of either liquid, but start a new thread for these- Preferably in whimsy)
Many members have boiled down virgin battery electrolyte (or other more or less dilute acid) when needing concentrated sulfuric acid.
If you have personal experience, please do share your density and/or titration results with us- With a good, careful write up of procedures you
followed, both in concentration and testing your final product. No assumptions, just the facts.
I have tested output of MY procedure, using a cheap deep fryer as a sand bath to 90% of the height of a 4000ml tall form beeker, starting with virgin
battery electrolyte. Density was 1.82, after air cooling the loosely covered beaker for minimal time @ 20% relative humidity to 20*C.
Density measurement was taken at 20*C on a 50ml sample in a 50ml graduate calibrated for that temperature, scale used was accurate to 1mg. BOTTOM of
meniscus aligned with graduation.
As I was satisfied that product was at least 90%, I used it as such. Results were in accordance with calculations, so no more formal titration testing
was done.
[Edited on 4-12-2015 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Deathunter88
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OK guys, let me get this straight:
ave369 made a device that allows him to make azeotropic 98% acid from battery acid in a 2 step process:
1st step: Battery acid is boiled in a RBF open to the air until white fumes begin to be evolved. Concentration is ~70%.
2nd step: The boiled down acid is added to the device he made which is a basically a retort connected to a liebig so the vapours cool enough in the
air cooled section to prevent thermal cracking of the water cooled liebig while at the same time preventing the awful white mist.
My understanding is that he originally planned to heat up the 70% acid to boiling point and distill. At first water with a small amount of acid is
condensed and he discards this (or he adds it to another batch of boiling battery acid to 70%) The ratio of acid to water rises until most of the
water has been carried over and he begins getting 98% acid as his distillate.
BUT since his stove overheated he only managed to get a few drops of 98% sulphuric acid distillate. However, if the distillate is at 98%
concentration, the acid left in the boiling flask should also be 98%. Thus in the end he was left with a few drops of very pure azeotropic acid and a
lot of azeotropic acid with some non-volatile contaminant. He seems to be content with this as he stated "now I have the technology and think true
distillation is overkill".
hissingnoise said that distilling 85% acid will result in 85% acid. Could he please clarify what he means by this? What I took it to mean is that if
you stuck some 85% acid in a flask, hooked it up to a condenser and boiled it, it would be impossible to collect something more concentrated than 85%
acid. However, this is not the case because the less volatile component (water) boils off, leaving the boiling flask's contents more and more
concentrated until reaching 98%, when it distills over azeotropically. Thus by keeping an eye on things and changing receiving flasks periodically it
is totally possible to concentrate 85% acid to 98% acid...
He also said that I had my knowledge of distillation "hopelessly confused". What exactly am I confusing? Copied from the dictionary on what 'distill'
means: purify (a liquid) by heating it so that it vaporizes, then cooling and condensing the vapour and collecting the resulting liquid. What ave369's
original plan by that definition is a distillation: he heated 70% acid until it vaporised, then he cooled the vapour and collected at first mostly
water, then water and acid, and finally azeotropic acid. What am I getting "confused" about?
edit: I did not see Bert's post since I was writing this post, sorry about that. But I feel that getting the science right is still very important.
[Edited on 4-12-2015 by Deathunter88]
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ave369
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And I'm a she, thank you very much. Still waiting patiently for the custom title "Eastern European Lady of Mad Science" I asked Polverone about, which
hopefully will resolve the confusion once and for all.
[Edited on 4-12-2015 by ave369]
Smells like ammonia....
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Magpie
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Here's a link to a vapor-liquid equilibrium (VLE) diagram for the system H2SO4/H2O. See Illustration 1. This shows the vapor concentration over the
whole range of distillation.
http://www.qvf.com/qvf-process-systems/mineral-acids/concent...
Here's a better VLE diagram:
http://www.mie.uth.gr/ekp_yliko/SulfuricAcid-Water_VLE_conce...
Attachment: SulfuricAcid-Water_VLE_concentrations.pdf (328kB)
This file has been downloaded 456 times
[Edited on 5-12-2015 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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hissingnoise
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| Quote: | | He also said that I had my knowledge of distillation "hopelessly confused". |
Well, you did seem to believe that distilling was the only route to obtaining concentrated acid which led me to think you'd never reconcentrated
dilute acid . . .
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