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Chemistry_Keegan
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[*] posted on 17-2-2013 at 08:00
Purification Of Acetic Acid From Vinegar


Does anyone have some really easy and efficient methods of purifying acetic acid from vinegar with the use of only household items? My vinegar is almost always five percent acetic acid and ninety-five percent water, if that helps at all.
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[*] posted on 17-2-2013 at 08:13


Fractionated distillation. Assuming that by 'purifying acetic acid' you mean obtaining a higher percentage of acetic acid (ethanoic acid).

Or react vinegar with slaked lime (Ca(OH)2) to obtain calcium acetate. Treat calcium acetate with sulphuric acid in a typical displacement reaction:

Ca(OH)2(s) + 2 HOAc(aq) ===> Ca(OAc)2(aq) + 2 H2O(l)

Concentrate the calcium acetate by boiling in:

Ca(OAc)2(s or aq) + H2SO4(aq) === > CaSO4(s) + 2 HOAc(aq)

Do it right and you can concentrate your acetic acid quite a bit.



[Edited on 17-2-2013 by blogfast25]




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[*] posted on 17-2-2013 at 13:53


i have heard that freezing vinegar should make the crystals precipitate out in the solution due to its higher melting point than water but i had no success with it tho..
it might be an effect called ''freezing depression'' but before you take that for true im not even sure what that is (:




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[*] posted on 17-2-2013 at 14:06


Quote: Originally posted by Antiswat  
it might be an effect called ''freezing depression'' but before you take that for true im not even sure what that is (:


No, freezing point depression is something else. FPD is what causes seawater to freeze a few degrees below the MP of pure water: the dissolved salt causes freezing point depression. In the past FPD was used frequently to determine the molecular weight of newly discovered substances.

To check if freezing vinegar will separate out either pure ice first, or a hydrate of acetic acid or even pure acetic acid itself, you need to consult a temperature-phase diagram for the system ethanoic acid/water. Personally I strongly doubt it...




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[*] posted on 17-2-2013 at 17:35


Quote:
EFFECT OF SWEATING ON THE PURITY IN MELT CRYSTALLIZATION
W. S. Choi, K. J. Kim
Crystallization Process & Engineering Laboratory, Department of Chemical
Engineering, Hanbat National University, Yuseong, Daejeon 305-719, South Korea


... From my off-line library, gotten from the web. Google it. Blogfast, you are wrong this time. I have done it.

Why do people capable of writing a post first not take the time to consult the web and UTFSE of this site. This topic has been covered numerous times. I do not have the patience or inclination to place the above by FTP on the site, or find the reference here to the subject on this sites for the lazy or stupid. {Not you, blogger, old pal! - you are usually right}.

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[*] posted on 18-2-2013 at 08:07


Does any one know if freezing would work ?
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[*] posted on 18-2-2013 at 08:32


I tried it and part of it freezes while the other doesn't. You could try it yourself and see if it works. Experimentation is the core of the scientific method.



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[*] posted on 18-2-2013 at 09:38


DerAlte, well I stand corrected, gladly by you!

Quote: Originally posted by K12Chemistry  
I tried it and part of it freezes while the other doesn't. You could try it yourself and see if it works. Experimentation is the core of the scientific method.


Sure but what you're saying isn't very scientific either. What temperature did you use? How much froze and how much not? And what was the solid: pure glacial acetic acid or some acetic acid/water containing phase?

Now I'm off to buy some distilled vinegar! :D

[Edited on 18-2-2013 by blogfast25]




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[*] posted on 18-2-2013 at 10:20


I don't know. All I'm saying is that it was left in there for about 3 days. If it was completely water it would have frozen solid. So it did purify to an extent. I'm suggesting to try it because it would be easier than asking on a forum.



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[*] posted on 18-2-2013 at 11:01


Quote: Originally posted by K12Chemistry  
I tried it and part of it freezes while the other doesn't. You could try it yourself and see if it works. Experimentation is the core of the scientific method.


Yes, but by UTFSE you can easily learn much and get fresh ideas:

I admit that this one is hard to find:

http://www.sciencemadness.org/talk/viewthread.php?tid=2194




Knowing that I can buy good quality NaOH, HCl, and H2SO4 locally gives me great peace of mind.
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[*] posted on 18-2-2013 at 11:08


Thanks Magpie.



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[*] posted on 22-2-2013 at 12:41


Why can't we just simply concentrate the acetic acid by boiling it? It has a boiling point of 118C
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[*] posted on 22-2-2013 at 13:57


Vinegar is only 4 -6% acetic acid so we have to use some method of stripping out the acetic acid in a pre concentration step before distillation.
Pyroligneous acid was used as a source of acetic acid and reaction with calcium carbonate, hydroxide or oxide was used to form calcium acetate, this was then filtered out and then heated with sulphuric acid to make acetic acid.
Another approach is to use diethyl ether or ethyl acetate as a stripping solvent.
Under optimum conditions this can remove all but 0.1% of the acetic acid and the solvent left in the water phase is stripped out before the water is discharged.
Distillation of the solvent acetic acid phase yields high purity acetic acid.
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[*] posted on 22-2-2013 at 17:38


Quote: Originally posted by ScienceSquirrel  
Use diethyl ether or ethyl acetate as a stripping solvent.
Under optimum conditions this can remove all but 0.1% of the acetic acid and the solvent left in the water phase is stripped out before the water is discharged.
Distillation of the solvent acetic acid phase yields high purity acetic acid.

This sounds a better system than the acetate/conc sulfuric acid method that I have used.
Perhaps used in combination with freeze concentration to bring the bulk of the dilute solution down somewhat.
Presumably the solvent phase is dried prior.Molecular sieve?

[Edited on 23-2-2013 by starman]




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[*] posted on 27-2-2013 at 02:21


If you Started off with 1000mls of house hold vinegar and boiled it down to about 100mls or so, and then added bulk Anhydrous Copper Sulfate (in intervals) could you eventually get a higher concentration of acid as the salt absorbs the water leaving the acid? then you can try crystallize it out by freezing it?
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[*] posted on 27-2-2013 at 02:51


Quote: Originally posted by DerAlte  
Quote:


Why do people capable of writing a post first not take the time to consult the web and UTFSE of this site. This topic has been covered numerous times. I do not have the patience or inclination to place the above by FTP on the site, or find the reference here to the subject on this sites for the lazy or stupid.

Have you ever heard the saying,"call no man a fool", probably not and even if you did, you would most likely not heed the warning.
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[*] posted on 27-2-2013 at 16:49


Quote: Originally posted by toothpick93  
If you Started off with 1000mls of house hold vinegar and boiled it down to about 100mls or so, and then added bulk Anhydrous Copper Sulfate (in intervals) could you eventually get a higher concentration of acid as the salt absorbs the water leaving the acid? then you can try crystallize it out by freezing it?


Unfortunately not that simple.Forms an azetrope,so you'd end up with 100mls of the starting concentration (maybe a slight increase.)




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[*] posted on 27-2-2013 at 20:15


Quote: Originally posted by starman  
Quote: Originally posted by toothpick93  
If you Started off with 1000mls of house hold vinegar and boiled it down to about 100mls or so, and then added bulk Anhydrous Copper Sulfate (in intervals) could you eventually get a higher concentration of acid as the salt absorbs the water leaving the acid? then you can try crystallize it out by freezing it?


Unfortunately not that simple.Forms an azetrope,so you'd end up with 100mls of the starting concentration (maybe a slight increase.)

My CRC assures me that water and acetic acid do not form an azeotrope. (D-12 of the 70th edition). However, the boiling points aren't that different, so if you boiled the solution at about 100oC, the vapour pressure of acetic acid would be 400 mmHg (D-199, CRC) times the mole fraction of about 0.02 so about 8 mmHg out of the atmosphere...the vapour you'd get off would be about 1% acetic acid (by number of moles). This is about half the concentration of the original vinegar, so if you boil off half of the vinegar, you'd increase the concentration of acetic acid from 5% to 7.5% (and the collected distillate would be about 2.5%).




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[*] posted on 27-2-2013 at 21:23


Grocery store generic brand distilled white vinegar is 6 % acetic acid.
You will need 4 gallons to obtain one quart near 100 % concentration.
For what it costs you to process you are better off buying.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350436824...

.
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[*] posted on 28-2-2013 at 06:38


You can also order direct from the same seller. http://www.dudadiesel.com/search.php?query=acetic

I've used them before and they sell to individuals.


[Edited on 28-2-2013 by hyfalcon]
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[*] posted on 28-2-2013 at 15:52


To get into Silver Chemistry, you may which to make Silver acetate from dissolving Ag in a Vinegar/H2O2 solution. As long as the solution remains acidic, the Silver acetate is soluble. Dilute and the Silver acetate could precipitate (I have made AgC2H3O2, but always kept it dissolved as a path to other silver salts).

Now, to make more conc Acetic acid, add a slight excess of the AgC2H3O2 precipitate to HCl:

AgC2H3O2 + HCl --> AgCl (s) + CH3COOH

remove the white Silver chloride from your new conc Acetic acid. To prepare HCl, see a recent thread.

No HCl, perhaps the following approach of passing an excess of CO2 into a cold conc AgC2H3O2 solution:

2 AgC2H3O2 + H2O + CO2 --> Ag2CO3 (s) +2 CH3COOH
--------------------------------------------------

Another path, place the AgC2H3O2 in a small amount of water and let it sit in sunlight. My speculation (and it is speculation as the only thing I have observed is that Silver acetate dissolved in Acetic acid will decompose in modest light in time with the creation of a grey Ag suspension and not Ag2O):

AgC2H3O2 + H2O --Light--> AgOH (s) + CH3COOH

2 AgOH ---> Ag2O + H2O

So on net:

AgC2H3O2 + H2O --Light--> 1/2 Ag2O (s) + 1/2 H2O + CH3COOH

and even more problematic is that this reaction seems reversible, so may only work in dilute solutions. It may be better to let the solution stand in light in open air as CO2 could help push the reaction.


[Edited on 1-3-2013 by AJKOER]
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[*] posted on 1-3-2013 at 09:55


Quote: Originally posted by AJKOER  
To get into Silver Chemistry, you may which to make Silver acetate from dissolving Ag in a Vinegar/H2O2 solution. As long as the solution remains acidic, the Silver acetate is soluble. Dilute and the Silver acetate could precipitate (I have made AgC2H3O2, but always kept it dissolved as a path to other silver salts).

Now, to make more conc Acetic acid, add a slight excess of the AgC2H3O2 precipitate to HCl:

AgC2H3O2 + HCl --> AgCl (s) + CH3COOH

remove the white Silver chloride from your new conc Acetic acid. To prepare HCl, see a recent thread.

No HCl, perhaps the following approach of passing an excess of CO2 into a cold conc AgC2H3O2 solution:

2 AgC2H3O2 + H2O + CO2 --> Ag2CO3 (s) +2 CH3COOH
--------------------------------------------------

Another path, place the AgC2H3O2 in a small amount of water and let it sit in sunlight. My speculation (and it is speculation as the only thing I have observed is that Silver acetate dissolved in Acetic acid will decompose in modest light in time with the creation of a grey Ag suspension and not Ag2O):

AgC2H3O2 + H2O --Light--> AgOH (s) + CH3COOH

2 AgOH ---> Ag2O + H2O

So on net:

AgC2H3O2 + H2O --Light--> 1/2 Ag2O (s) + 1/2 H2O + CH3COOH

and even more problematic is that this reaction seems reversible, so may only work in dilute solutions. It may be better to let the solution stand in light in open air as CO2 could help push the reaction.


[Edited on 1-3-2013 by AJKOER]


You are having a laugh?
Silver is very expensive and this method is wildly impractical compared with the classical method of calcium hydroxide to make calcium acetate and then sulphuric acid or solvent stripping and distillation.
Acetic acid can be readily purchased anyway.
It is not controlled and has a myriad of uses such as weedkilling, cleaning, etc. I can buy 25% acetic acid in the hardware section at the supermarket and 100% acetic acid from a lot of places on the Internet.
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[*] posted on 1-3-2013 at 12:32


DONALD W wrote:

Quote:
Have you ever heard the saying,"call no man a fool", probably not and even if you did, you would most likely not heed the warning.


I assume by this you mean some Biblical quote. You should have finished the quote to properly define it, because there are a thousand quotes about fools. Here are a trio:

Before a man speaks it is always safe to assume that he is a fool. After he speaks, it is seldom necessary to assume it. H. L. Mencken

The wise man does at once what the fool does finally. Niccolo Machiavelli

Fools rush in where angels fear to tread.

Be that as it may, I did not call anyone a fool. My words were: I do not have the patience or inclination to place the above by FTP on the site, or find the reference here to the subject on this sites (sic) for the lazy or stupid.

We are all lazy and/or stupid from time to time. You do not have to be a fool to qualify.

You must realize, as a member of a few weeks standing, that for old hands who have been hanging around this forum for years, seeing the same old subjects come up time and time again becomes very tedious. To us it appears lazy to not do a little basic research on the subject in hand. Did you Google it? Has it been discussed previously in SM?

Re stupid, I am assuming anyone capable of posting coherently here is also capable of using a search engine. Admittedly the search engine on SM is not a sophisticated one, but it will show a lot if presented with “acetic acid”. Try it. A five minute search gave me the following (I did not read any,however):

http://www.sciencemadness.org/talk/viewthread.php?tid=19698&...
http://www.sciencemadness.org/talk/viewthread.php?tid=17976&...
http://www.sciencemadness.org/talk/viewthread.php?tid=13818&...
http://www.sciencemadness.org/talk/viewthread.php?tid=2194&g...
http://www.sciencemadness.org/talk/viewthread.php?tid=12261&...
http://www.sciencemadness.org/talk/viewthread.php?tid=9155&g...
http://www.sciencemadness.org/talk/viewthread.php?tid=8794&g...
http://www.sciencemadness.org/talk/viewthread.php?tid=7775&g...
http://www.sciencemadness.org/talk/viewthread.php?tid=6824&g...
http://www.sciencemadness.org/talk/viewthread.php?tid=5528&g...
http://www.sciencemadness.org/talk/viewthread.php?tid=5528&g...
http://www.sciencemadness.org/talk/viewthread.php?tid=4498&g...
http://www.sciencemadness.org/talk/viewthread.php?tid=2194&g...

I do not know how many of these are useful. But the very last one, the oldest one, the one mentioned by Magpie in this thread, is probably the very best. Seek and ye shall find!

I guess this a plea that all new members read The SM Guidelines by our erudite and illustrious Nicodem : http://www.sciencemadness.org/talk/viewthread.php?tid=19143, preferably before rushing into posting. Read and digest.

There are no rules here. The forum is 10 years old and has accumulated an enormous number of postings and repetition is inevitable. This can be minimized by adding to existing threads without opening endless new ones on the same topic.

@ Chemistry_Keegan
Please do not feel that this directed at you. It is a general comment. Your question was a perfectly valid one, but might have been better directed to Short Questions or Beginnings.

@blogfast – I admire your patience in continuing to provide guidance to tyros. If only I had a small shred of that patience!

Apologies to all for an off-topic rant, but I felt it had to be said…

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[*] posted on 1-3-2013 at 12:38


@ScienceSquirrel

Re: You are having a laugh?

AJKOER = anagram of A JOKER - I always get the impression he is speaking tongue-in-cheek or having us on!

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[*] posted on 1-3-2013 at 19:01


OK, if you have to go out and buy Silver, yes this may not be your best choice. If you are interested in Silver Chemistry and happen to have some silver items laying around, go for it!

And yes, I agree, Acetic acid is one item best purchased, but If you enjoy using chemistry, I do find Silver Chemistry fun (most prefer shopping).

I happened to find two Silver candle holders and as my spouse have completely forgotten they existed, and as she doesn't read my threads, I 'recycled' them. Actually, once you have invested in (or created) silver salts, they can, indeed, be easily recycled. For example, if your final product is AgCl use NaOH+Sugar (actually glucose from the action of NaOH on the Table Sugar) to get back to Silver. Also, unlike Pb, I am not worried about toxicity issues.

I read one of your suggested threads. It used Sodium acetate and H2SO4 and then distilled :( to remove the Na2SO4 impurity and concentrate. I will take my simple, safe and nearly free (once you have may your initial Ag investment) silver chemistry approach any day. Do you notice that one of my preparations involved photodissociation, how cool is that (most likely impractical by the way, but still cool).

Now, I do refer to this employment of Ag as Silver Chemistry because it has interesting (and useful at times) differences. For example, adding NaOCl to a soluble Silver salt forms AgOCl which rapidly, in absence of an excess of Ag2O, creates AgClO3, a chlorate.

3 AgOCl --> 2 AgCl (s) + AgClO3

Now, little known for example, is that AgClO3 is readily decomposed by HCl (and also with time on its own) to AgCl and O2, but with HOCl, my recent research suggests, the formation of some Chloric acid (cool :D). Compare this preparation to another (albeit, a very bad one) for HClO3, like boiling a Chlorate with H2SO4, and if you avoid the explosion and/or the acid burns :o, you deserve an award, perhaps a book on Silver Chemistry :cool:.


[Edited on 2-3-2013 by AJKOER]
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