woelen
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tantalum hydroxide -- reactivity?
I can obtain 250 grams of tantalum hydroxide, high grade, for less than EUR 10. Is this simply Ta(OH)5? Is it worth the money, or is this material so
inert that I can't do anything with it, except maybe a thermite reaction?
I would like to experiment with Ta in aqueous solution, but before I spend that money I want to be sure whether I can get it dissolved (e.g. in acids
or strong bases).
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The_Davster
A pnictogen
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Tantalum and niobium chemistry are very very similar, the metals are similarly unreactive, and the same goes for the oxides. I have a feeling the
hydroxide will be just as bad...these metals do not like aqueous much!
Not much 'net info on it, first page of google results has an ebay listing for it...perhaps the same one...
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woelen
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Well, I ordered the stuff, because I could combine it with something else, which I really wanted, without extra shipping costs. Now I have 250 grams
of Ta(OH)5 for GBP 6 (appr. $10) and I can only say wow, what a chem.... NOT NOT  .
I think that the glass of my test tubes is more reactive than the tantalum hydroxide . Heating it in conc. HCl does nothing, reacting with conc. NaOH is useless. The best I could obtain is adding the stuff HCl (30%) to which some
H2O2 (30%) was added. That slurry turned pale yellow/green, and even there, I doubt this is due to the tantalum, it might as well be some chlorine,
formed from the H2O2/HCl-combo. I think it is thermite-time. A mix of red P, Al and Ta(OH)5 should do something interesting, don't you think so.
From that same seller I had WO3, and that is an interesting chem. WO3 easily dissolves in aqueous NaOH, giving Na2WO4 and that can be dissolved in
strong HCl. It gives beautiful colors with reductors, very similar to the molybdenum blues. Tungsten also can do that.
It seems that at very high concentration of HCl also oxochloride compounds of W(VI) can be formed, somewhat similar to chromyl chloride. More to be
told about that later....
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garage chemist
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Maybe you can dissolve it in an NaOH melt?
Remember chromium(III)oxide, the green pigment which won't dissolve in acid or base- you have to stir it into molten NaOH (nickel, iron or best silver
crucible)while adding KNO3 to convert it to soluble chromate.
Maybe something similar is in order for your inert tantalum compound.
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