barley81 - 26-3-2012 at 15:28
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...
<p>
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?
strontiumred - 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]
blogfast25 - 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.
barley81 - 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.