Text 6646, 100 rader
Skriven 2006-10-17 08:24:14 av mark lewis (1:3634/12.0)
   Kommentar till text 6618 av JOAN MACDIARMID (1:123/140)
Ärende: Vinegar
===============
 ML> i also had to google "reagent grade" as well as "glacial acetic
 ML> acid"... whoa! that's some interesting stuff!

 ML> 98% pure water free acetic acid

 JM>  Jim W. caught us in this! 98% is tech grade, not reagent grade. 

hunh? in my reading, i understood that "98% pure water free" is what made GAA
glacial...

 ML> explosive when mixed with air (or was that oxygen?)
 ML> at "low heat" temps (38.9C, 102F)

 JM>  Nah. I think that only means it's easily flammable
 JM>  in air if ignited. It doesn't go off spontaneously.
 JM>  Freezing isn't a problem, after all. You warm it
 JM>  up, it melts into the same liquid it was before
 JM>  it crystallized.

 ML> =======================================================================
 ML> === Concentrated acetic acid is corrosive and must therefore be handled
 ML> with appropriate care, since it can cause skin burns, permanent eye
 ML> damage, and irritation to the mucous membranes. These burns or blisters
 ML> may not appear until several hours after exposure. Latex gloves offer
 ML> no protection, so specially resistant gloves, such as those made of
 ML> nitrile rubber, should be worn when handling the compound. Concentrated

 JM>  I am surprised to hear latex offers no protection.
 JM>  At least it would slow stuff down on its way to your
 JM>  skin so you could rinse the glove. But if one were
 JM>  planning to get right down into the stuff, like
 JM>  handling objects submersed in the acid for some
 JM>  reason, special gloves probably would be a good
 JM>  idea.

yeah, no doubt :)

 ML> acetic acid can be ignited with some difficulty in the laboratory. It
 ML> becomes a flammable risk if the ambient temperature exceeds 39 øC (102
 ML> øF), and can form explosive mixtures with air above this temperature
 ML> (explosive limits: 5.4%-16%).

 JM>  OK, that's the flash point. It can in most cases
 JM>  be handled safely at this point, but one would need
 JM>  to avoid ignition sources. Not a problem in most
 JM>  chemical labs, but a likely problem in uncooled
 JM>  storage warehouses or shipping trucks in the summer!

yep... and make sure there's no lit bunsen burners near by O:)

 ML> Solutions at more than 25% acetic acid are handled in a fume hood
 ML> because of the pungent, corrosive vapour. Dilute acetic acid, in the
 ML> form of vinegar, is harmless. However, ingestion of stronger solutions
 ML> is dangerous to human and animal life. It can cause severe damage to
 ML> the digestive system, and a potentially lethal change in the acidity of
 ML> the blood.

 JM>  As with most things, concentration is the key!

very true...

[trim]

 ML> how do you pronounce "carboxylic"??  car box ee lick??

 JM>  Americans would probably do so, or car box ILL ick (to put the
 JM> stress  in the right place. Brits might use a long I (eye) in the
 JM> third  syllable...they pronounce ethyl as EE-thile, anyway.

ahh, thanks... i stumbled over that word a few times when reading about GAA to
my father and a few friends...

 JM>  If I spilled glacial acetic
 JM>  acid on my hands, I would probably find it
 JM>  irritating and walk (not race) to the nearest
 JM>  sink to rinse it off. Sulfuric or nitric acids
 JM>  would blacken the skin almost immediately and
 JM>  leave a fearful burn if not washed off

 JM>  Of course, when I am handling any concentrated
 JM>  acid I am wearing some sort of gloves. Even flimsy
 JM>  vinyl ones give you a few seconds to react to a spill,
 JM>  back away and strip the gloves off, removing the
 JM>  acid with them. I am not stupid.

i hear that!

 JM>  [Splitting message: I try to keep them less than 100 lines] 

 JM> ___ Blue Wave/386 v2.30 [NR]
 JM> ___ Platinum Xpress/Win/WINServer v3.0pr5
 JM>  - Origin: Try Our Web Based QWK: DOCSPLACE.ORG (1:123/140)

oops, sorry... i normally don't even think about message lengths... the
reader/editors i use don't have much of any limits on them if they do have
limits...

)\/(ark

 * Origin:  (1:3634/12)