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Author: Subject: Titanium
barley81
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[*] posted on 26-3-2012 at 15:28
Titanium


Hello everyone.
I recently dissolved some fireworks-grade titanium powder into some hydrochloric acid for this experiment:
http://woelen.homescience.net/science/chem/exps/titanium/ind...
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I left the solution loosely stoppered in its tube for one day. Afterwards, it was deep violet-blue and looked similar to the web-page's sample. I left it for another two days. It turned a darker shade of violet, less blue. It's even a tinge grayish at some angles. Is this due to aerial oxidation? I burned off the hydrogen when the titanium was finished reacting. It seems strange that it would turn a different color. Shouldn't it just fade as TiO<sup>2+</sup> ions form?
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strontiumred
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[*] posted on 27-3-2012 at 02:48


Yes - I got exactly the same thing. Became almost a red wine colour after a week or so. It may be a chloro complex forming slowly, perhaps [TiCl4]- ?

See here: http://woelen.homescience.net/science/chem/exps/expshow.cgi?...

[Edited on 27-3-2012 by strontiumred]
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blogfast25
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[*] posted on 27-3-2012 at 11:16


Ti [III] is very sensitive to oxidation: air oxygen will push it back up to [IV], the 'normal' OS of Ti. Search the forum.



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barley81
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[*] posted on 27-3-2012 at 13:40


@blogfast I know that already (in my first post in this thread, I mentioned that the color should only fade instead of changing if it were simple oxidation). I searched the forum and found Strontiumred's post about titanium complexes. Thank you for reminding me.


@strontiumred
Thanks for the link. I might try this with sulfuric acid to see if the initial indigo color doesn't change. I looked in the SM library and did a quick Google search, but couldn't find that much information about titanium complexes. I will search more.
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