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- From: khartman@fnalf.fnal.gov
- Newsgroups: sci.materials
- Subject: Re: Cleaning Calcium chips
- Date: 10 Jan 93 01:23:29 -0600
- Organization: Fermi National Accelerator Lab
- Lines: 47
- Message-ID: <1993Jan10.012329.1@fnalf.fnal.gov>
- References: <C0K42H.C75@max.physics.sunysb.edu> <1993Jan9.191208.1187@Princeton.EDU>
- NNTP-Posting-Host: fnalf.fnal.gov
-
- 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
-