Intergalactic_Captain - 12-11-2007 at 13:32
My dad gave me a 5-lb coffee can full of metal turnings for my birthday (no cheapo 4th of july next year!), but we don't know what metal it is. The
only thing he remembered about where it came from is that it is all the same metal, from one machine running one job, but it could be either
Titanium, Magnesium, or Aluminum.
The fact that the surface is still shiny on 95%+ of it makes me stray away from aluminum and magnesium, but I've never seen titanium that milled like
this - I believe they're lathe turnings, very fine.
So, anyone know of any simple analytical methods to determine which one it is, or even which one it isn't?
The_Davster - 12-11-2007 at 13:36
Dissolve in HCl(with heating if it is Ti)
If it is purple in solution, it is titanium
If not, basify the solution, both Mg and Al hydroxides will ppt. Continue adding base, if the ppt redissolves, you have aluminum, if it does not
redissolve, it is magnesium.
[Edited on 12-11-2007 by The_Davster]
bereal511 - 12-11-2007 at 13:36
Take a little bit of the turnings, and if it doesn't dissolve in dilute hydrochloric acid, it's titanium. If it doesn't dissolve in a concentrated
solution of sodium hydroxide, it's magnesium. If it dissolves in both, it's aluminum.
I think that's right.
[Edited on 12-11-2007 by bereal511]
not_important - 12-11-2007 at 17:52
To get the purple/blue Ti(III) you need an excess of the metal and keep air away from it (stopper with some cotton), although it will form close to
the dissolve metal but fade out quickly. Adding H2O2 to the solution will first change it to colourless, then to yellow-orange.
Titanium will likely be an alloy with a few percent of other metals, which can give unexpected colours and odd results with other tests. Vanadium and
aluminum are both common alloying metals, if I'm remembering correctly.