chucknorris
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Unknown powder, lets find out what it is
I discovered this substance a year ago from my warehouse box, and there it was: about 200 grams of obviously hygroscopic, clumpy, pure white dry
powder. I picked it up to my table where it was for a month or two, until I packed it back when I did cleansing, and then I forgot it again.
Now, it is there again, and I wanna find out, what it is. I actually thought it could have been ammonium perchlorate or sodium perchlorate, since I
was in fireworks those times, but Im not sure. I have very faint picture that I actually tried to burn it with some metal powders a year ago with no
success, so I wont bet that it really is perchlorate, so it could be anything.
What tests should I carry out to find out what this is, so that I lose the least amount of substance? What I think first are the solubility, melting,
boiling or decomp. points, reactivity with other substances, etc.
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Hexavalent
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There have been many threads on chemical analysis previously, please use the search engine.
For now, look into testing for halides with AgNO3 (followed by addition of ammonia solution), flame tests, reactions with acids etc.
This video summarises well some important wet analytical techniques;
http://www.youtube.com/watch?v=TF71ffRRpKE
The melting point and boiling point, if its an ionic solid, will probably be quite hard to determine as ionic compounds generally have very high
values for these due to the very strong interionic bonds.
These tests can be done in micro test-tubes, so the amount you use will be minimal. Actually, it may be a good idea to prepare a stock solution of
your compound/mixture, and simply transfer a few ml at a time to each tube, saving you time and probably some of the chemical.
[Edited on 19-12-2012 by Hexavalent]
[Edited on 19-12-2012 by Hexavalent]
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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morry-cule
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I think you have it about right. Check out:
Organic Chemistry Laboratory Survival Manual (available in .pdf)
Page 72
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woelen
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If the powder is white, then you can rule out many transition metals like vanadium, chromium, copper, nickel, etc.
Before doing anything analytical I would do a few basic tests, which can rule out many many things.
- is it soluble in cold water? in hot/boiling water?
- if you strongly heat the material without flame contact, does it char? (if it does, then almost certainly it is an organic compound of decent
complexity)
- is it flammable? test this by heating the material with flame contact
- If it is soluble in water, does the solution in water conduct electrical current? If yes, then you know it is a salt or an acid of appreciable
strength.
After these basic tests you can start systematic qualitative analysis methods. Which tests you want to do depend on the outcome of the basic tests,
mentioned above.
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chucknorris
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Thanks for the tips! I'll take a look about those and see what I can find out. Not gonna be posting results this evening though, I've got a move to
do, just packing my lab and stuff up on road. 
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