Ethanoic Acid - Flammable?

[Ferdinand]

A colleague of mine ignited propanoic acid. The resulting smell was described as quite unsettling for him and some of his students. He then attempted to ignite glacial acetic acid which does have a flammable symbol on the reagent bottle. However, he could not ignite it. Can anyone enlighten(no pun here) us high school chemistry teachers why we weren't able to ignite flammable glacial acetic acid?

 

Thanks

 

Ferdinand

[YT2095]

I just tried this myself and mine burns ok, nice blue flame, and that was the liquid that was at the Outside of the solid block in the middle of the bottle.

how old is the GAA? and was it stored 100% sealed?

 

the closed cup flash point should be 42c.

[Ferdinand]

Thanks for your reply. Interestingly, our GAA is very old - >15 years but there's no solid block ..it's all liquid...

 

Have you burned propanoic acid? If so...what's the "interesting" smell?

 

Nando

[YT2095]

I`ve never burned that, I don`t have any, but I shouldn`t imagine there would be any smell at all if it was a complete combustion and the product itself was clean, same with GAA, there`s no smell when it`s on fire, only just when it`s out in the open before you light it.

for your GAA, if you have a fridge with a temp control, put it in there and take it down to 16c and leave it overnight, if it doesn`t freeze you`ve probably absorbed water over the years, and then it will be a little harder to light.

 

 

sorry but I haven`t the remotest idea why it should smell at all?

[woelen]

I have 80% acetic acid, and that is not flammable at all. So, even absorbing a relatively small amount of water may render the stuff completely inflammable. Also, the stuff I have does not freeze at all, not even near 0 C.

[Tartaglia]

Ethanoic acid and water form a eutectic mixture

[YT2095]

Azeotropic, (eutectic normaly applies to solids).

[raivo]

I have 80% acetic acid, and that is not flammable at all. So, even absorbing a relatively small amount of water may render the stuff completely inflammable. Also, the stuff I have does not freeze at all, not even near 0 C.

 

I do not know about 100% acetic acid but those that i have (various from 80% to 98%) are quite hard to crystallise. For example one sample in PET bottle did not crystallise although was in fridge at -18C during two months. After using some of it for experiments and placing into fridge again it crystallised after some hours completely. Now, again, i liquified it and after this it stays more than week in fridge without crystallisation.

 

Another day I pipetted 98% acetic acid. Room temperature was 20C but glassware was somewhat colder and acetic acid crystallised completely inside pipette even before i managed to fill it completely! This was scary as i did not expect something like that!

 

So acetic acid does what it likes to do. At least if we talk about crystallisation.

[YT2095]

I put mine in the fridge (only 5c) and some hours later it was frozen solid like concrete, when I took it out I put it back in the store room, and a few days later there is Still a solid block in the middle

it`s very strange stuff, esp when Mega pure, Gallium is similar too, it would seem there is some sort of Hysteresis in the Melting/Solidifying points.

Gallium once molten and taken below it`s MP, can stay molten for quite some time, even though another peice (not been melted) will remain solid

 

it reminds me a little os super saturated Sodium Acetate, it will remain liquid until mechanical shocked, and then crystalise almost instantly giving off much heat

 

 

Long Live Chemistry!

[Borek]

Azeotropic, (eutectic normaly applies to solids).

 

Not sure about details, but this mixture can be both eutectic (when it solidifies) and azeotropic (when it boils).

 

Best,

Borek

--

General Chemistry Software

www.pH-meter.info

[Tartaglia]

I think a little lesson in the meaning of azeotropic and eutectic is needed here. They do not apply to single states they apply to changes of states. Eutectic applies to solid/liquid change of state and azeotropic to the gas/liquid change of state. Thus Borek is right both azeotropic and eutectic apply to liquids mixtures as liquids both freeze and boil