Chemophiliac - 6-6-2007 at 17:59
I recently grew some fairly large crystals of FeCl2*4H2O but I'm wondering how to preserve them so they don't oxidize or dry up. I'm currently keeping
them in a vial of mineral oil but I don't know if this is in fact a good method. What do you guys suggest?
Fleaker - 6-6-2007 at 18:26
Cast resin around them?
Protactinium - 29-9-2007 at 00:57
Fleakers suggestion would be your best way to go, they have clear epoxy as a super glue. For ordinary storage, if you could get a hold of some
nitrogen (welding supply stores usually have it) or argon those are probably your best bet, or the other alternative could be to vacuum seal the
container (they used to have this thing that would vacuum seal food by a hand pump that would seal nearly anything reopen it and use it).
Antwain - 29-9-2007 at 23:48
Unfortunately using vacuum is not an option it will cause the crystals to lose water. I can't tell you how to keep them perfect, but this may help...
Store them in a cool place, this will cut down on efflorescence.
Store them in a container with a very small airspace and no leaks. Once the oxygen has been consumed, no further oxidation can occur.
Protactinium - 5-10-2007 at 22:34
Good point, I guess I wasn't thinking cause FeCl2 4 H2O isn't the stablest, although you could briefly vacuum (very low) and surge argon into the
container maybe. Although anhydrous FeCl2 could withstand medium vacuum very well.
Engager - 11-10-2007 at 18:31
Clever chemists use Mohr salt to store Fe(II) unoxidised. Mohr salt is simple ferric-ammonium sulphate double salt, witch is easily prepared and
purified.
[Edited on 12-10-2007 by Engager]
UnintentionalChaos - 11-10-2007 at 18:38
^The point is to preserve some impressively grown crystals, not to store the salt for future use. I've heard about storing in a fairly small, well
sealed container with a bed of small cyrystals of the same material under the specimen to help establish a properly humid atmosphere with as little
(if any visible) efflorescence on the specimen as possible.
If they seem to be fine in the mineral oil, I'd leave them because it will probably damage them more to take them out and clean them off than to just
leave them where they are.
16MillionEyes - 11-10-2007 at 19:28
Perhaps if you wrap it around in one of those plastic food covers and then keep it in a sealed cool flask might do the trick. I think the mineral oil
is the best choice though and you won't have to worry about losing your water to the oil except, perhaps, if it evaporates.
DerAlte - 29-10-2007 at 11:03
I happened to stuble on this thread by chance. Recently I had a strong solution of iron, sulphate, chloride and magnesium ions from a process I had
completed. Iron and chloride were in excess. I had left it out, intending to get rid of it - it was that disgusting dirty brown oxidized iron color.
When I poured out the brown liquid, at the bottom there was a neat pile of well formed crystals. I wrongly assumed they were FeSO4.7H20 but decided it
would be a good idea to dry and keep them to show my grand daughter. The sulphate heptahydrate is alleged to be insoluble in EtOH. I tried washing
with it, and it seemed these dissolved, so I quickly fried them and bottled them.
To my chagrin, a day later they had seriously deteriorated by oxidation. I am sure, now, they were chloride like you have.
Was the color a beautiful light green?
Mineral oil sounds good to preserve. They don't like air, that's for sure!
Der Alte