hodges
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Registered: 17-12-2003
Location: Midwest
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Stored 3 Years
Its been about 3 years since I've messed around much with most chemicals. I was taking an inventory today, and here are are some of the worst
casualties of storage I found. In the right front, you see a plastic bottle that was filled with CaO. Apparently air got in, likely forming CaCO3
and CaOH, which apparently occupy more volume. As you can see, the bottle expanded and cracked the plastic.
I store my reagents in a cabinet. Two reagents stored there are HCl and concentrated NH4OH. Everything stored in that cabinet eventually gets
covered with a coat of NH4Cl (I assume that is what it is - I have verified the presence of Cl in the substance using AgNO3 and verified the presence
of NH4 using NaOH). You can see that the large bottle of muriatic acid is covered with NH4Cl (with even large crystals forming in places). Likewise
for an ordinary glass stored in the same cabinet (I washed another glass that was also covered and placed it in the picture for comparison).
All my hydroxides except for one mostly used bottle are in good shape (they still rattle). I did find one other problem - some gold chloride crystals
have absorbed water and are now in solution. However, I'm sure I can dry these as I did originally. Calcium carbide is partially decomposed (some
powder mixed in), but I still have about say 70-80% of it left undecomposed. I'm not sure how my concentrated NH4OH or 30% H2O2 fared - have not
tested the strength of these yet.
Hodges
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Mr. Wizard
International Hazard
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Registered: 30-3-2003
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You can safely assume ANY HCl solution in a plastic bottle will find it's way into the air. That's why the windows in any lab are coated with a white
haze. This also explains the coat of rust on any iron stored in the same room.
Thanks for the graphics.
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a_bab
Hazard to Others
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Registered: 15-9-2002
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Mood: Angry !!!!!111111...2?!
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It has been discussed a million times here; some chems are not long term compatible with some plastics. HCl is known to diffuse from the HDPE bottles,
that's why there is a "shelf life" printed on them. Ammonia is worse, but HDPE is an acceptable option for it. Nitric acid gives the same issues.
Moreover, it eventually turns the HDPE brittle, thus an extra hazard.
On the other hand, acetone/alcohol(s) could be stored in HDPE, but not chloroform, as it will diffuse fast. There are tables on the net with
compatibilities.
For long time storage (2 years +) special reagent glass bottle with teflon lined cap is the best solution. Even then, in say 10 years some of the acid
vapors will eventually escape, rusting away the metallic shelfes, mixing up with the smell of bromine, iodine, and God knows what organic volatile
reagents, making new coumpounds, reacting togeter, and creating that "chemistry lab" smell we all love. It's chemistry, after all...
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Picric-A
National Hazard
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I seem to have no problem with my bottle of HCl.
Its a 1 litre bottle of 35% from a reputable supplier and i have had no problems with rusting/NH4Cl vapour around.
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grndpndr
National Hazard
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Anything wrong with a plain food grade type glass gallon bottle with approprate teflon cap for HCI storage?
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chemrox
International Hazard
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No-these work well for most things. Some vapors work their way through almost any capping system or seal so a ventilated storage area for acids,
halides and acid halides is usually used.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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