if GAA has been used before but was recapped immediately and stored in its original container at room temperature, does it have a short storage life?DJF90 - 23-2-2009 at 10:28
I dont see how GAA would break down. It might absorb atmospheric water but so long as you keep it tightly capped then this shouldnt be a problem.Sauron - 23-2-2009 at 11:08
I concurr. GAA is as oxidized as it can get, so how is it supposed to "break down"? whatever that means anyway.
Sitting in its original container it isn't going to turn into ketene.
It isn't going to spontaneously reduce to acetaldehyde or ethanol.
If it takes on some water from the air, shame on the bottler, but just dry it and redistill per the standard procedures in the usual texts
(Purification of Laboratory Chemicals) and the GAA is as good as new. Not one molecule of acetic acid will have "broken down" - it isn't a Yugo.vulture - 23-2-2009 at 15:05
Quote:
GAA is as oxidized as it can get
Not entirely correct, but for all practical purposes, GAA does not show any air induced oxidation. Just pointing this out to prevent some loon from
mixing GAA with chromic acid or, heaven forbid, Mn2O7, just to prove you wrong.
[Edited on 24-2-2009 by vulture]EmmisonJ - 23-2-2009 at 16:31
thanks guys, i know i can always count on this board on clearing things up
it's something someone told me (misinformed me apparently) via word of mouth and i wanted to see what the pro's had to say about itchemrox - 23-2-2009 at 18:30
Well .. not quite. I have no idea how long because it depends on humidity of where it's kept and how long the cap is off at a time and how many times
the cap comes off in a year but GAA stops being GAA and becomes AA eventually. It does not 'break down' as has been mentioned; at least not in
practical terms. @Vulture: what happens when you put CrVI in it? I just about ran down the hill to see for myself.Sauron - 23-2-2009 at 20:02
The thread poster is talking about the stuff auto-oxidizing or otherwise undergoing chemical change. He is not talking about taking on water. GAA and
95% acetic acid are chemically same. One is just anhydrous. Dry the wet Aa and it is GAA again.
Nor is he talking about throwing in Cr(VI). Of course yoiu can chew it down to C and CO and CO2, where do you reckon the carbon on filament of a
ketene lamp comes from if you are burning GAA in it?
So no, my remark was not "wrong" by the conditions stated. You can't impose a massive shift in the premise like that.
CH3COOH left alone in glass is going to remain CH3COOH.
Elves are not going to add chromic acid in the wee hours of the morning.
[Edited on 24-2-2009 by Sauron]Sedit - 23-2-2009 at 23:04
Put it this way EmmisonJ the one thing that annoys me about carboxylic acids is there stability, If they would just decompose on the fly I would be a
happy man.
Do a search and see if you can find a way to chemicaly reduce them down to an alkyl chain and report back... that will pretty much answer your
decomposition question.
~SeditPHILOU Zrealone - 24-2-2009 at 02:04
Quote:
Originally posted by Sauron
It is not even flammable. That ought to tell you something.
-With a flashpoint at 40°C, I doubt it to be "not even flammable". After all it is roughly equivalent to an equimolar mix of CH4 and CO2... so
flamable but tempered by the CO2 moiety... (CH3-CO2-H vs CH4 + CO2)Sauron - 24-2-2009 at 02:44
Ah, you are right. I wonder what I was thinking of.
