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BlindedAchievement
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Acid Concentration/purification
On my first post, I learned that to concentrate dilute sulfuric acid, you must distill it. My question to you is how. How in the world do you distill
a dilute solution of sulphuric acid?
[Edited on 21-1-2009 by BlindedAchievement]
[Edited on 22-1-2009 by BlindedAchievement]
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DJF90
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UTFSE
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BlindedAchievement
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what does that mean?
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hissingnoise
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It means "use the fucking search engine" a standard retort reserved for questions displaying apparent laziness.
You have, I think, some texts awaiting your reading skills. . .
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BlindedAchievement
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I looked, couldn't find anything. It's wierd, Google, ask.com, and yahoo only give me results about using distilled ingredients with sulfuric acid,
nothing about the actual process.
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DJF90
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I typed in "distilling sulfuric" and got plenty of hits on the forum search engine. (TFSE - not the fucking search engine, although it feels
appropriately named so at times).
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sparkgap
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If you really want on Google...
http://www.google.com/search?q=site%3Asciencemadness.org%20d...
Note how the searching was suitably restricted... 
sparky (~_~)
"What's UTFSE? I keep hearing about it, but I can't be arsed to search for the answer..."
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hissingnoise
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The best SE is at the top of this page. . .
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kclo4
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I think there should to be a tutorial written on how to properly UTFSE. It might help a lot of people by showing all of the tricks, such as
Filetype DF, Site:, etc.
BlindedAchievement, what were some of the search terms used?
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BlindedAchievement
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that I used or the computer gave me?
Now, I just found a way to distill the acid in my favorite encyclopedia.
What it said was that the basic way to do it was to heat the acid, in this case, a dilute acid, and bring the contents into a tube inside a conntainer
full of cool water (without letting the water go in) Apparently, the 95-98% sulfuric acid should appear in the tube. Well, I will u
[Edited on 21-1-2009 by BlindedAchievement]
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DJF90
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Doesn't sound like you've done a distillation before... why dont you practise with something innocuous like water, that way when it goes wrong you
wont be putting yourself in as dangerous as a situation.
If you insist on going ahead, distill the dilute acid. The first distillate will be (mostly) water, and as the bp raises to that of the concentrated
acid (95-98%), switch recieving flasks. IIRC conc. sulphuric boils at~340C, and at that temperature I wouldnt like to have an accident with it. This
concentration should be obtained without successive distillations.
An easier way would be to just boil of the water, and stop once the majority of it has been removed. This way you dont have to distil the sulphuric
acid. Just stope when you see dense white fumes being evolved from the boiling liquid. Preferably do it outside, and dont breath the fumes.
[Edited on 21-1-2009 by DJF90]
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hissingnoise
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The concentration of dilute H2SO4 is increased by heating to drive water off by evaporation.
It isn't distillation!
And it isn't something that should be entered into lightly or with inadequate understanding of the process involved.
Read the threads, particularly the parts on evolved vapours.
Whatever you do, don't go at it gung-ho!
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BlindedAchievement
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I ordered a lot of new apparatus that will be necessary in this experiment, but they won't come for a few more days, plenty of time to study up on the
experimentation, its hazards, and its execution.
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Magpie
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Here's something I ran across that you may find useful:
http://www.crscientific.com/newsletter-8.html
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not_important
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This too may be of interest
http://www.qvf.com/en/ProcessSystems_3/Mineral%20Acids/Conce...
It points out that when concentrating above 70% H2SO4 you need some sort of fractionating to reduce loss of acid in the steam. That also should serve
as a warning when concentrating by simple boiling, when the liquid temperature starts rising above 150 C there will be noticeable amounts of H2SO4 in
the vapour.
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S.C. Wack
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You won't need a column. The amount of acid given off is really quite small until it gets pretty hot, I've concentrated quite a bit of battery acid
both in the oven and in flasks. Let's call it 70% H2SO4 at 160C. According to this table from Perry's, the partial pressure of the acid under those
conditions is 0.005 mm.
Attachment: perrys_2007.pdf (53kB)
This file has been downloaded 666 times
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Ozone
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| Quote: | Originally posted by BlindedAchievement
... they won't come for a few more days, plenty of time to study up on the experimentation, its hazards, and its execution. |
I just noticed that the Doom-meter increased by approximately 25 mD.
Measure twice. Cut once.
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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BlindedAchievement
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You might have noticed I changed the name of this thread to "The General Synthesis of Aacid Concentration/Production," from "Sulfuric Acid
Distilation."
The main discussion here was about concentrating/purifying sulfuric acid, so let us expand this to the general concentration/purification (for our
convenience, let us only refer to this term as c/p) of acids.
[Edited on 21-1-2009 by BlindedAchievement]
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starman
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| Quote: | Originally posted by hissingnoise
The best SE is at the top of this page. . . |
You've got to be kidding.If I had one criticism of SM it would be the crappy search engine.Use the google site: type query suggested by sparky.
Start searching through acids of interest,one by one. Nitric ,formic,hydrobromic might get you started.As you begin to learn you will see they are all
different animals and general considerations that encompass them all can only be addressed at the most basic of levels.
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hissingnoise
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Er, OK; most convenient, then. . .
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BlindedAchievement
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I do have in my current pocession a 30-32% and a 7% concentration hydrochloric acid. I have already tested the process of distillation on saltwater,
and after a while I finally got the execution just right. I am now going to phase two; distilling a low concentrated acid. For this, I will use my 7%
solution of hydrochloric acid, and see how it works out. If it goes well, I will up the concentration level to my 18-20% sulfuric acid, and observe
the outcome. The final phase of this introductory concentration will be with the 30-32% hydrochloric acid.
If any of you are in pocession of descent tubing, a glass test tube (I will use 13x100 mm), an erlemeyer flask (best around 250 ml), holed stopper,
and a heat source, I encourage you to try it out with a low concentration acid (which would be best). It will be interesting to compare results.
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harrydrez
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Just so you know, you don't really want HCL to be any more concentrated than 30-32%. Also, you might want to look up fractional distillation.
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Sauron
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The new improved thread title is gibberish. Why not simply call it "Concentrating Acids" ? Don't try to sound inportant by concoting meaningless
sentences. You come off like Rush Limbaugh on a bad day.
Sic gorgeamus a los subjectatus nunc.
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BlindedAchievement
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Well, I suppose that for all acids, heating it to drive of the water is what we are refering to as distillation. I guess you don't need all the
apparatus I suggested. Just an evaporation dish or some heating container. Pour the acid inside and heat. The water should escape, leaving behind high
concentration sulfuric acid, hydrochloric acid, etc.
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Formatik
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You mean concentration by boiling? Concentration by boiling doesn't work for all acids. It is harder for some than others. Easy for H2SO4.
And you best know what the boiling azeotrope of the acids is. A lot of compounds form azeotropes with water, and so at a certain concentration they
will just boil away as soon as the acid hits that concentration. Azeotrope basics: http://en.wikipedia.org/wiki/Azeotrope
Then here is an exemplery chart of azeotropes of various two-component systems. Sulfuric acid and water form a maximum azeotrope at 93.3% wt at regular
atmospheric pressure at 338°C. Below that temperature, the water boils off. This allows concentration of weaker sulfuric acid by boiling.
If you were to boil 30% HCl, then you would de-concentrate it because of the maximum boiling azeotrope of 20.24% HCl at about 110°C. The fumes and
mist from heated HCl are also more volatile than H2SO4. With lower concentrations, it is the opposite, it is known e.g. below 12% conc. will lose a
part of the H2O and get more concentrated if it's heated.
And acetic acid which pure acid has a boiling point of 118.1°C, reportedly has more or less (none) of an azeotrope with water (but as the water boils
off at a lower temperature, the acid also seems to come off because it is somewhat volatile, another plus by sulfuric acid concentration it has a very
low volatility, so I doubt concentration of the acid to anything using a low concentration at regular atm pressure and basic equipment, I've tried
with 5% acid and it didn't work).
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