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In article <C0K42H.C75@max.physics.sunysb.edu> danube@max.physics.sunysb.edu writes:
>    I have some chips of Calcium that are badly oxidized.  I am wondering
>if there is a simple way to clean them.  I put them in a plastic bottle
>with N2 gas and sealed it for storage.  I noticed that if I shake the 
>bottle a lot, the oxide rubs off a bit.  I suppose I could put glass chips
>in the bottle and shake for a day.  Then I could take the Ca chips out in
>a glove box.
>    Any better Ideas?  Also, how can I store things like Ca, Na, K, and Rb
>without oil?  Is Carbon-tetrachloride better?  I need to put the chips in
>a high vacuum system and I don't want the oil around.  I assume things like
>C-tet evaporate more easily.
>							Danube


Under no circumstance should you allow an alkali metal to contact any
halogenated solvent.  T. L. Davis (The Chemistry of Powder and
Explosives, p. 402) describes the exciting reaction of sodium with
chlorform (CHCl_3); it is bound to inspire confidence if repeated in
your lab.  Even with alkali earths, these solvents should not be 
assumed to be chemically inert.  You might consider rinsing the 
oil off using a light hydrocarbon, such as hexane or cyclohexane 
(--after checking with someone knowledgable (not me!)).

In article <1993Jan9.191208.1187@Princeton.EDU>, gjmelden@phoenix.Princeton.EDU
(Gregory J. Melden) writes:
> In article <C0K42H.C75@max.physics.sunysb.edu> danube@max.physics.sunysb.edu
> writes:
>>    I have some chips of Calcium that are badly oxidized.  I am wondering
>>if there is a simple way to clean them.  I put them in a plastic bottle
>>with N2 gas and sealed it for storage.  I noticed that if I shake the 
>>bottle a lot, the oxide rubs off a bit.  I suppose I could put glass chips
>>in the bottle and shake for a day.  Then I could take the Ca chips out in
>>a glove box.
>>    Any better Ideas?  Also, how can I store things like Ca, Na, K, and Rb
>>without oil?  Is Carbon-tetrachloride better?  I need to put the chips in
>>a high vacuum system and I don't want the oil around.  I assume things like
>>C-tet evaporate more easily.
>>							Danube
> 
> 
> Under no circumstance should you allow an alkali metal to contact any
> halogenated solvent.  T. L. Davis (The Chemistry of Powder and
> Explosives, p. 402) describes the exciting reaction of sodium with
> chlorform (CHCl_3); it is bound to inspire confidence if repeated in
> your lab.  Even with alkali earths, these solvents should not be 
> assumed to be chemically inert.  You might consider rinsing the 
> oil off using a light hydrocarbon, such as hexane or cyclohexane 
> (--after checking with someone knowledgable (not me!)).


	The above advice is sound, the Alkali Metals can react violently
with solvents.  Try checking in _The Merck Index_ under the individual
metals.  Storage liquids are listed.  You might not want Carbon Tetrachloride
in your vacuum system either.  From what I have read, CCl4 is difficult to
remove from a vacuum system (at least when it is used to clean out a diffusion
pump, for example).  I normally use Acetone.

	I'm not sure what you are doing with your vacuum system.  If you are
using a diffusion pump for your high vacuum, you might get "backstreaming",
where a small amount of oil will contaminate the vacuum chamber.  If this is 
the case, you might be better off using a light storage liquid for the K, Na,
etc., and letting the liquid evaporate under vacuum.

	As far as cleaning the Calcium that you have now, you might just want
to order new Ca.  I think the new Ca comes packaged under an inert gas to
prevent oxidation.  Hope this helps.



Ken