Eclectic
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Chromium Trioxide
Has anyone here worked with pure anhydrous chromium trioxide? All the descriptions I'm reading say it's a dark red or orange material, but mine looks
dark violet to me, almost like tiny iodine prills. Also, I need to repackage from the original metal container into smaller units to avoid exposure
to moisture from multiple openings. Any thoughts on compatibility issues with LDPE, HDPE, and Polypropylene? I'm sure the various Teflon plastics
are OK, but that's a very expensive option. I'd like to avoid glass due to breakage issues, and metal due to corrosion, but plastic bursting into
flames isn't good either. 
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chloric1
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Well, just as a curiousity, back in 2003 I precipitated Chromic acid by adding concentrated sulfuric acid to an almost boiling
solution of potassium dichromate(since the sodium salt was not available for me at this time). It was a scary process and the mixing made angry
noises
I remember a crystaline material deep red in color with a slightor very slight violet hue. Unfortunately, I did not keep it because I did not have a
fritted glass disk to wash the crystals with cold concentrated nitric acid to remove the sulfate ion.
Fellow molecular manipulator
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Eclectic
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JEEZE this stuff is evil corrosive! The Nalgene compatibility charts only list the fluorinated resins as compatible. I guess it's glass, metal or
Teflon.
PVC seems to be OK. Anyone ever seen heavy wall wide mouth hard PVC jars?
[Edited on 11-8-2007 by Eclectic]
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The_Davster
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I have used it extensively for oxidations (not in home lab).
The stuff I used was in some sort of fused flakes, and were a very dark red, it reminded me of iodine as well.
The stuff is nasty, I do not like it all that much. I would say store it in a glass bottle, and if you are worrying about it breaking, cover the
glass bottle in ducttape, so if it ever breaks you dont have a carcinogenic spill on your hands...
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Eclectic
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I've got a few Nalgene 1L Teflon widemouths that will work for my own use. I was thinking I might sell 2 lb lots to reduce my inventory, but after
reading the hazmat and DOT info and looking at the containment issues, it would probably be more responsible to sell the excess to an electroplating
company.
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Xenoid
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Christ! The things one discovers 40 years after the event!
As a teenager in the '60s I was in the fortunate position of having a mother who worked in the chemical store of a major scientific establishment in
Australia. She regularly brought me home bottles of chemicals which had been returned and earmarked for disposal. One was a 500g jar of chromium
trioxide, it was in the old style ground glass stoppered containers, so no problem there. I just treated it like any other oxidizer and all of it
ended up in various pyrotechnic mixtures. I even remember grinding it with sugar and sulphur in a mortar and pestle, leaving my shed for a few minutes
and returning to find the whole mess on fire!
Carcinogenic eh!.... gulp!
Regards, Xenoid
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chemrox
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| Quote: | Originally posted by chloric1
Well, just as a curiousity, back in 2003 I precipitated Chromic acid by adding concentrated sulfuric acid to an almost boiling
solution of potassium dichromate(. |
This is the precipitate I get when mixing chromic acid glass cleaning solution? I thought I was being carelss about saturation and leaving too much
K2Cr2O7 undissolved.
"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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Eclectic
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I think the main culprit involved with CrO3 carcinogenicity would be inhalation of ultra fine chromic acid mist from plating tanks, generation of
volatile chromyl chloride, or contamination of drinking water. It's probably unwise to bring ANY useful synthetic reagent into intimate contact with
your personal organic chemistry.
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Xenoid
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| Quote: | Originally posted by Eclectic
I think the main culprit involved with CrO3 carcinogenicity would be inhalation of ultra fine chromic acid mist from plating tanks.....
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I once took some XRF sample holders around to a small chrome plating shop to be replated. The old guy who I dealt with had green tinted hair, I
exaggerate not! It was like a green version of the blue rinse that older women are so fond of. I guess Cr accumulates in the hair like arsenic does.
Regards, Xenoid
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12AX7
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At least it was green and not orange. Green Cr(III) isn't a problem, but it
begs the question how the Cr(VI) was reduced!
Tim
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Eclectic
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Probably copper rather than chromium. Lots of grinding and polishing of copper undercoats in a decorative chrome shop.
But I don't think Cr(VI) would survive long in living system. Isn't oxidation of organic substrates a likely mechanism for it's toxicity?
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panziandi
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I have 250g of CrO3 in a HDPE bottle and another 250g in a glass jar. The former resembles iodine to some extent but in large chunks which are
deliquescent and forms a dark red smear (as you drag a piece across a surface! - not recommended mind!), I believe it's "fused", the later is in the
form of fine crystal powder which I haven't ever opened. The HDPE bottle is a few years old and seems to have held the CrO3 very well indeed, no
seepage through the walls and the product is fairly dry (despite being half filled). 
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