Is glacial ethanoic acid soluble in water?

[ATB_roo]

In terms of it's structure

Thanks

[periwinkle]

ethanoic acid is soluble in water, the hydrogen leaves the -COOH to form H+ and COOH- making the solution acidic. I think it is quite stable something to do with sharing the electrons across the double bond.
but i don't actually know what glacial ethanoic acid is

[nescio]

periwinkle
glacial ethanoic acid is pure, water free ethanoic acid. It is called glacial, because it freezes at 16.7�C

[terambulan]

Yes! :)

[terambulan]

and No!:)











Only soluble in salt water

[theprof]

nescio, glacial ethanoic acid is NOT pure and water-free. In my university laboratories, we use the highest purity grades of ethanoic acid on a daily basis and our main supplier, Sigma - Aldrich, only guarantees up to around 99.8% purity. Now whilst the remaining 0.2% is not necessarily all water, analysis shows that in most batches, a trace of water is present. It is simply not possible to manufacture 100% pure ethanoic acid. Standard glacial acetic acid is generally around 99.5% pure with slightly more water present.

The basic Sigma-Aldrich catalogue can be looked at online without an username/password if you'd like to see the range of glacial ethanoic acids available.

Incidentally, it is called glacial simply because it looks like glacial ice after freezing. It has absolutely nothing to do with the 16.7 degree figure.

terambulan, I've yet to see a sample of ethanoic acid that is only soluble in salt water.

[nightmare]

theprof
(nescio is my alter ego)

I acknowledge your accurate answer.
I merely meant to say that glacial ethanoic acid is of fairly high purity, with little water and because its melting point is 16.7�C, will tend to freeze in cold weather. I appreciate it is essentially impossible to achieve 100%, water free purity.

[theprof]

Thanks for that nightmare.

I corrected you as there is quite a difference between the terms "water free" and "with little water" as you put it in your last post. I'm glad that you appreciate the difference as I often come across students who think that "glacial" is synonymous with anhydrous. It's not.

The second sentence of your first post does seem to claim that ethanoic acid is called glacial because it freezes at 16.7 degrees C. I can't see how else it could be interpreted regardless of the comma. The second sentence does read as if the 16.7 figure has such a special scientific significance that anything that freezes at that temperature could be prefixed "glacial". This was the reason for my penultimate paragraph.

The point I was making was that the temperature it freezes at is immaterial ie it wouldn't matter if it was 8.35 degrees C, 4.17 degrees C or any other temperature. It is called glacial simply because it resembles glacial ice.

Anyhow, you've shown me what you meant to say and there's no harm done. I'm glad that you've also realised that the 16.7 figure is the correctly referred to as the melting point and not the freezing point.

Forgive the pedantry � I put it down to marking too many examination papers over the years!

[terambulan]

Here, Under Section 3, first aid

http://cameochemicals.noaa.gov/chemical/2272

[nescio]

theprof,
I too tend towards pedantry. My excuse in this case is that I was attempting to give an answer in fairly simple terms and that because the melting point is similar to the temperature of a cool room, it will solidify in cold weather.
I remember the bottle of "glacial acetic" on the school lab shelf doing so in Winter.

[theprof]

terambulan, you said "only soluble in salt water" in your second post.

That is not correct. Ethanoic acid is soluble in water, most alcohols, diethyl ether, glycerol and most other organic solvents. That means that it is miscible with a good few thousand solvents.

Yes, of course ethanoic acid is soluble in "salt water". However this has nothing to do with the salt the water contains: it is soluble in water anyway.

Consequently, bearing in mind the ease of miscibility of Ethanoic acid with other organic solvents, in no sense is it true that Ethanoic acid is "only soluble in salt water" as you put it.

[theprof]

nescio, I understand the need to provide an answer in fairly simple terms. However, from personal experience, I have found that that there are a few people on AB who will challenge an answer unless it is, let us say, 100% correct.

Consequently, I tend not to put myself in the firing line by simplifying answers to too great an extent on AB despite my policy of basing my answers upon my judgement of the likely age and knowledge of the poster.

Funnily enough, I too remember the 250ml glass stoppered reagent bottle of "glacial acetic acid" in the cold and draughty lab in my secondary modern school behaving exactly as you describe. I didn't realise how cold affected the acid until I was "promoted" to the local grammar school where the acid was kept in an indoor storeroom.. Thankfully, the winchesters of Ethanoic Acid in my university chemical stores are kept at controlled temperatures although sometimes we deliberately freeze it for enzyme experiments.