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Author: Subject: Tungsten Compounds from W Electrodes
ciscosdad
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[*] posted on 22-6-2011 at 23:23
Tungsten Compounds from W Electrodes


I have a couple of tungsten electrodes and have wondered about dissolving them to explore tungsten chemistry.
The search engine reveals little on the forum, and a (brief) search of my chemistry texts yields only that it is acid resistant and requires a fused alkali with an oxidiser (KNO3?) to dissolve.
Is anyone aware of any interesting references, or other sources of practical information?
Potential hazards would also be useful information. I assume that being a heavy metal, it will be wise to be cautious about toxicity and disposal.
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Intergalactic_Captain
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[*] posted on 23-6-2011 at 00:01


If a search doesn't pull it up, I must not have posted it here - A while ago, I was interested in tungsten for tungstic acid for use in some odd oxidation reaction. I've been going through my old stacks of journal articles recently, and I think I know where the refs are - If I find them I'll post them for you... What I do remember is a reaction involving NaOH and H2O2 to form sodium tungstate, no specifics till I find the papers.

Are you interested in anything in particular? If you do a forum search for thorium compounds, you'll find quite a bit on working with tig rods. Until my dad was layed off, I had almost unlimited access to used tig electrodes - only catch was I had no way to know which ones were thoriated and which ones weren't...




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not_important
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[*] posted on 23-6-2011 at 12:20


Not a lot of detail, but :

http://www.cleanroom.byu.edu/wet_etch.phtml (click on 'tungsten') sez 2 NH4OH : 1 H2O2


As I recall, 30% H2O2 at 40-55 C works, added alkali speeds it up a little and gets the W as more easily isolated tungstate

While proper disposal is always a good idea, tungsten and its compounds are not overly toxic. Toxicity in military applications has been related to W-Ni_Co alloys, with dust being inhaled or bits being embedded into tissue; in these cases Ni has well established toxicity as does Co to a lesser degree.


http://www.mod.uk/NR/rdonlyres/8062F2B1-6A9A-42F8-B819-17890...
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bob800
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[*] posted on 23-6-2011 at 12:51


There's a section in Experimenting with Chemistry, Experiments for the Home Lab by Burton Hawk on tungsten chemistry:http://books.google.com/ebooks/reader?id=RLUNAQAAIAAJ&pr... (page 55). It involves fusing the filaments with molten NaOH to produce sodium tungstate (be extremely cautious if you attempt this, molten NaOH will eat through glass!). However, I think not_important's method would be safer.
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ciscosdad
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[*] posted on 23-6-2011 at 20:25


Thanks for your responses.
The heads up on Thorium from W electrodes was instructive.

Any Journal References or other refernences would be appreciated as well.

My chemistry resources are limited. The simple electrolytic dissoltion may be all I can manage at least for the forseeable future. Maybe precipitate a little thorium, just to say I've done it.
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[*] posted on 24-6-2011 at 02:45


Just to obtain the oxide, place the filament in an enclosed space, such as a covered beaker. Attach mains voltage to each end. A brilliant flash should be observed and there should be yellow smoke floating around. Wait for it to land on the walls of the beaker. This is anhydrous tungsten trioxide. It is rather unreactive.



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albqbrian
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[*] posted on 27-6-2011 at 01:03
About the electrodes...


What are the basic dimensions of the W electrodes? Purity? Price?

Thanks???
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LanthanumK
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[*] posted on 27-6-2011 at 02:57


Are they pure tungsten electrodes, thoriated tungsten, ceriated tungsten, or lanthanated tungsten?



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