11 replies to this topic

[darkfang77]

I want to try and make sodium acetate this summer as an experiment.
I understand how to make it and I want to use pure acetic acid and sodium hydroxide.
I have plenty of sodium hydroxide and i just need the acetic acid.
I don't have the equipment to distill vinegar and it would be too inefficient so I am hoping to crystalise it. Wikipedia says it crystalises at 16.5 degrees so if I put it in a fridge, then it should freeze?
Unfortunately it does not. I have some industrial grade malt vinegar (>65% acetic acid) and after a week in the fridge : no result.
I tried putting it in the freezer, IT IS STILL THERE. It has been two weeks and not even a crystal. =(

Something interesting which happened though, I hope someone can explain the following phenomenon:
1. After a few days in the freezer, drops of a clear liquid condensed somehow on the top of the container.
2. When the tapped the top of the container, a few drops fell into the solution of industrial vinegar.
3. The strange part: I heard a hissing/fizzing sound when the drops of clear liquid fell into the solution.

So are there any methods to gain pure acetic acid from vinegar of ANY grade?

Any suggestions would be appreciated. Thanks

[dr thrust]

why not buy the pure form of acetic acid and save yourself the hassle?

[seymour]

Or react the vinegar with Sodium bicarbonate (so you can judge the reaction's completion roughly by when there are no more bubbles), and then purify the sodium acetate via recrystallization?

[darkfang77]

why not buy the pure form of acetic acid and save yourself the hassle?

Where's the fun in that?
Plus, I have checked eBay for it, (no results).
I do have a seller of pyro chems, but he does not sell it (no surprise). Oh and I want to save as much money as poss.

This isn't really helpful =/

[CCH Concepts]

i brought some acetic acid on ebay the other day.

http://cgi.ebay.co.u...e=STRK:MEWNX:IT

[darkfang77]

i brought some acetic acid on ebay the other day.

http://cgi.ebay.co.u...e=STRK:MEWNX:IT

Why didn't this come up when i searched it?
The seller also sells the highly coveted hydrochloric acid. But not Nitric =(

I am still hoping to find a more homemade solution to the problem, but at least I have a last resort.

[CCH Concepts]

try these guys, ive brought nitric and sulphuric from them.

http://www.abbey-chemicals.co.uk/

they will expect to be sent copy of photo id and to fill out disclaims stating you not making drugs, but the prices are good.

[darkfang77]

try these guys, ive brought nitric and sulphuric from them.

http://www.abbey-chemicals.co.uk/

they will expect to be sent copy of photo id and to fill out disclaims stating you not making drugs, but the prices are good.

hmm. I don't think they'll be too happy to find out that I'm not even 18!
I am currently making sulphuric acid myself using electrochemistry.
Once I have enough sulphuric acid, I can use it as a catalyst to make nitric acid as I have nitrate salt.

But still, does anyone have any idea what I should do with my industrial grade vinegar as this is the main reason I started this topic? It won't crystalise!

[plastics]

Water free/anhydrous or glacial acetic acid is notoriously difficult to prepare on a non-industrial scale from more dilute forms of the acid. It is also rather unpleasant stuff. However some clues can be found here:

https://www.sciencem...d.php?tid=12898

Unfortunately as you will see most use sodium acetate as the starting point

This begs the question why do you need glacial acetic acid at all; why not use your more dilute form

Most people making basic non-organic nitrates/sulphates etc don't use 100% fuming nitric acid or oleum as their raw materials

[dr thrust]

a use for your vinegar?, ive heard its good for making pickles and putting on chips but i may be wrong!
ive used stronger grades for cleaning copper and brass components of model steam engines! brings em up a treat

Edited by chris m, 01 August 2010 - 11:08 PM.

[Mumbles]

I think you're confusing purity and concentration. Your malt vinegar should be pure, but just not 100% concentrated. Honestly, even 99% acetic acid is hard to crystalize. You really need to get it close to 100% to get it to crystalize at 16 degrees. Generally you have to distill it off from sodium acetate and sulfuric acid. Your stuff is still pure, but just has water in it which will evaporate off.

If you take sodium bicarbonate, and your malt vinegar, you will end up with pure sodium acetate once the liquid is evaporated and solid is dried. If you're careful, you can make a solution that heats up once it crystallizes!

[darkfang77]

I think you're confusing purity and concentration. Your malt vinegar should be pure, but just not 100% concentrated. Honestly, even 99% acetic acid is hard to crystalize. You really need to get it close to 100% to get it to crystalize at 16 degrees. Generally you have to distill it off from sodium acetate and sulfuric acid. Your stuff is still pure, but just has water in it which will evaporate off.

If you take sodium bicarbonate, and your malt vinegar, you will end up with pure sodium acetate once the liquid is evaporated and solid is dried. If you're careful, you can make a solution that heats up once it crystallizes!

I understand that the vinegar is pure, etc. However, I didn't understand that even pure acetic acid is difficult to crystalise!
Let's say that the acetic acid won't crystalise because it is contaminated with the malt flavourings, etc. Can anyone tell me why the water in the vinegar won't freeze because that's the bit I do not understand??
Furthermore, why did the solution hiss/fizz when drops of condensation fell into it??

Reason I want a really pure acetic acid instead of mixing a weak solution of vinegar is because 65% concentration means I need less compared to a 5% vinegar, and I really don't want to have to stoichiometrically measure 5% solutions and I don't have a lot of spare sodium bicarbonate but I have plenty of sodium hydroxide to spare!