YT2095 - 11-1-2008 at 07:47
I`m currently dissolving Th 232 in HCl.
it`s not only generated way too much heat for such a Non vigorous reaction (it`c now in ice water to cool it).
but the product color is all wrong???
ThCl4 Should be soluble and a white to grey solid.
Nope, this has made a load of Black insoluble matter at the bottom of the test tube and the liquid part is like a clear grey color? (perhaps
particulate black matter in the acid).
the test tube is Brand new, the HCl is the same batch as I`v used over that last 4 years without issue, and I have No way to explain this at all??
anyone?
12AX7 - 11-1-2008 at 08:07
Dissolving metals sometimes has that effect. Aluminum does it, and probably most iron alloys. I would guess intermetallics and trace compounds
(e.g., C, Si, etc. -ides).
Tim
YT2095 - 11-1-2008 at 09:39
well this was sold as 99.5% pure, there`s way too much junk to be impurities, it`s almost 90% of the overall original metal volume and there still an
appreciable amount of (now black) metal to be dissolved 
but the Main question is Which fraction do I keep?
if it`s of Any significance (although I doubt it) this sample is from the 1950`s.
this black Could be carbon, or UO2 or MnO2 or even CuO to look at, it`s really quite disappointing, as I wouldn`t have expected 0.5% to have occupied
so much space.
not_important - 11-1-2008 at 10:37
Check the delta-H on Th + 4 HCl => ThCl4 + 2H2, and then consider the reaction of thorium metal with water and the hydration and hydrolysis of
ThCl4.
You say that's there's metal remaining, which suggests most of the HCl has reacted. If so it is likely some ThCl4 has hydrolysed to the hydroxide.
Remove the metal, add HCl until there is an obvious excess, and see if the solution doesn't mostly clear up.
The half percent of other stuff could darken the hydroxide, which would likely be a somewhat gelatinous glop. Getting the hydroxide back into
solution would let you see the true amount of impurity solids. Centrifuging would remove most of the suspended solids at that point.
YT2095 - 12-1-2008 at 05:59
well having left it overnight in a 10% HCl soln, there is Still some metal in there fizzing away gently, along with that heavy black PPT, I say heavy
because upon mixing it sinks quite rapidly to leave the clear(ish) soln again.
this will however make it reasonably easy to decant later before I convert it to the Hydroxide and ultimately the Nitrate (I`m trying to make one of
the Original old style gas mantles).
this Black material is still very unexpected though, esp when you consider that I only used 100mg of the metal (I considered that to be sufficient for
a single mantle).
the Hydroxide Should be White, so it`s not that, the Chloride a white/grey, so it`s not that either???
YT2095 - 12-1-2008 at 10:39
interesting observation, the metal how now all been dissolved with the assist of gentle heating, leaving the soln and the black ppt at the bottom.
it Does catalyse H2O2 though, much in the same way that MnO2 does.
I`m hoping I can exploit this to dissolve the whole lot as a Chloride now.
I have read that ThO2 can sometimes become Black over time, Perhaps that`s what has happened here but by some other mechanism other than time.
unionised - 12-1-2008 at 12:08
iirc Th and U produce hydrides as a side product when dissolved in non oxidising acids.
YT2095 - 12-1-2008 at 12:55
Hydrides, great
I have never dealt with them before and know nothing about their nature, I think I`m going to have to "Cap" this rxn for now (when it settles) and
store it away for a while, and do some more research during this time.
I`d rather get it Right than dick about stumbling in the dark, this stuff was quite expensive and hopefully the end result will be worth it 
not_important - 12-1-2008 at 17:08
unionised has it right, from The Radiochemistry of Thorium, dissolving thorium metal in HCl leaves a good percentage of the weight of metals
as a dark solid. This can be dissolved by adding a small amount fluoride to the reaction products after the metals as all been reacted. You could do
this in a polythene container at 40 C or so. Add a soluable fluoride to the still acid (from HCl) mix, a bit at a time - stirring until no more
change is observed, then a bit more fluoride and repeat until most or all the dark solids are gone.
BTW, I would use aqueous ammonia to precipitate the thorium hydroxide, it tends to retain alkali metal ions which might cause problems when making the
gas mantle.
while older and mostly targeted at radiolab applications, the radiochemistry of thorium still has some generally useful information. The LANL site
isn't aways up, and may be gone now as the Bush Administration has been shutting down many public access governmental libraries, so I've included a
link to another source of that document.
http://library.lanl.gov/cgi-bin/getfile?rc000034.pdf
http://www.fas.org/sgp/othergov/doe/lanl/lib-www/books/rc000...
unionised - 13-1-2008 at 13:18
"I think I`m going to have to "Cap" this rxn for now "
I wouldn't seal it up if I were you; wet hydrides slowly give off H2 and you really don't want that stuff bursting the bottle.
YT2095 - 14-1-2008 at 03:28
well I`m pleased to report that after reading your second link several times (the LANL site was down), I used the Ammonium hydroxide as suggested and
now have a very clean looking hydroxide, I decided to decant the clear fraction away from the PPT.
as it turns out (again thanks to the info in that document) that the PPT next day had changed color to a gray/green almost Olive color, as it was left
sitting in the H2O2 and HCl, it would seem it`s made the Peroxide Th2O7. I may just store that for a later date if I ever come across something
interesting that requires it.
I don`t Currently have any fluoride salts (that situation is being Rectified shortly), but all in all I`m quite pleased with the Hydroxide that I have
now and the quantity, it will be more than plenty.
Thank you each for your Help! 