D4RR3N
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How to store Lanthanum metal
I purchased a large ingot of Lanthanum metal for an experiment i have not got round to completing yet. The metal came vacuum sealed in a bag but when
I received it the bag had been cut (i think customs did it to see what was in the bag). I put the metal into a vacuum jar I got from a food store and
pumped out the air.
Its not working fully though as I can see white oxide building up on the surface of the metal. Apart from putting it under oil what else can I do to
stop the oxidation. I would rather not put it under oil, is there something I could put in the jar which will absorb the oxygen.
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Pomzazed
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Maybe oxygen trap will work? like pyrogallol or some phenolic group that draws out oxygen from the air.
Don't stare at me making fumes... I'm just experimenting with some gas...
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JohnWW
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La metal should be kept out of contact with air or water, as its surface fairly rapidly reacts to give both La2O3 and LaN. Having an electronegativity
comparable to that of Mg, it may ignite when put in a flame, and being pyrophoric, may react explosively if finely divided. It should be kept in
either a hard vacuum, or under argon, or under a light mineral oil.
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woelen
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I have a similar problem with pieces of praseodymium. I store this under a layer of ligroin (40 .. 60 boiling range). This protects it from air and
moisture and when I need a piece of the metal, I take it out of the volatile liquid, which evaporates in seconds and I'm left with a nice dry piece of
metal. I store my calcium, sodium and potassium in the same way. The only thing is that you must be absolutely sure that the vessel in which the metal
is stored is tightly sealed. The highly volatile liquid should not evaporate leaving the metal uncovered.
I also noticed, that initially, there is some reaction of the metal, but this stops after a while. This is due to traces of water and traces of
oxygen, dissolved in the ligroin.
Similar results can be obtained with hexane, heptane or cyclohexane, whichever is cheapest or easiest to obtain. I advice against using pentane,
because that it really low boiling (35 C or so).
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IrC
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Use the oil. My 3 pound chunk does best in oil (keep container air tight) and if I need to cut off a piece to experiment it cleans easily with a
solvent. Air drying with warm air helps, it does not oxidize that quickly. My several pound chunk of Eu is much more reactive to air, the La not so
bad.
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D4RR3N
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I live in the UK, anyone know a read available source of a light mineral oil. I was thinking of purchasing a large bottle of clipper oil. I know that
"baby oil" is mineral oil but it has a sent added so not suitable.....any thoughts?
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not_important
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You usually can find unscented mineral oils, or plain lamp oil, with a little searching. Make sure it is mineral oil and not vegetable oil based, as
many 'natural products are. Oil for treating wooden butcher blocks and cutting boards is often plain mineral oil.
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len1
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Its tempting to use a low bp liquid such as hexane to store alkali metals and the like. Anyone who tried clearing parafin off Na or K will know what
a pain that is. Only trouble is that the usual low bp liquids are very flamable. A drop of water on tweazers used to extract K out of hexane will
ignite the
K, and kaboof.
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not_important
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That in part is why it used to be common practice to store and cut reactive metals under kerosene or mineral oil, and wash the needed pieces with
petroleum ether. My university labs usually had a wide mouthed rinse bottle of pet ether used for the preliminary rinse by dunking, the pet ether
from the 2nd rinse in a beaker or flask being added to the rinse bottle.
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D4RR3N
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Quote: Originally posted by not_important  | You usually can find unscented mineral oils, or plain lamp oil, with a little searching. Make sure it is mineral oil and not vegetable oil based, as
many 'natural products are. Oil for treating wooden butcher blocks and cutting boards is often plain mineral oil.
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True, I have seen clear lamp oil in garden stores near those outdoor burners. I am tempted by Woelens suggestion but I don't think I'm going to find
something like that off the shelf.
Probably easier to go to a garden store and pick-up a bottle of lamp oil.
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panziandi
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D4RR3N Buy liquid paraffin from the local chemist. It its viscous like glycerol, I use this in preferance to lighter fractions because it contains
less water. You can heat it in a dish to >100oC to dry it if you want to, or can use it as is (slightly moist but not an issue). I place the metal
into this and there can be a slight bubbling but not much. Then top the jar up, to minimise air space, then tighten the lid.
Remove the metal, rince with dry pentane/hexane/heptane/ether and dry then transfer to your reaction etc. This is my standard technique with Li, Na, K
and the rare earths.
Bottles of this paraffin are obtainable from "small" "independent" chemists and perhaps from high street ones too. It's odour free and used for
constipation etc. About £1.50 for 150mL i think.
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indigofuzzy
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If you're speaking of the kind of mineral oil used to treat constipation, this is available in the us at any corner pharmacy and most grocery stores.
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D4RR3N
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| Quote: Originally posted by panziandi | D4RR3N Buy liquid paraffin from the local chemist. It its viscous like glycerol, I use this in preferance to lighter fractions because it contains
less water. You can heat it in a dish to >100oC to dry it if you want to, or can use it as is (slightly moist but not an issue). I place the metal
into this and there can be a slight bubbling but not much. Then top the jar up, to minimise air space, then tighten the lid.
Remove the metal, rince with dry pentane/hexane/heptane/ether and dry then transfer to your reaction etc. This is my standard technique with Li, Na, K
and the rare earths.
Bottles of this paraffin are obtainable from "small" "independent" chemists and perhaps from high street ones too. It's odour free and used for
constipation etc. About £1.50 for 150mL i think. |
Thanks for that panziandi, I'm going to need a few bottles so guess their going to think I must be very constipated 
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a_bab
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In France at least it is sold in vet farmacies by litre (5 eur/L) in the form of a fairly thick clear odor free oil.
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