sbreheny
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Old decomposed Titanium (III) Chloride
Hi all,
I recently bought an old (I'd estimate 30 years old) bottle of what was supposed to be a 20% solution of TiCl3. I didn't pay much and didn't expect
too much. When it arrived, instead of a purple solution, there was a milky white suspension with considerable precipitate in the bottle - all of it
yellowish white. The liquid is quite acidic - pH of about 1 to 0. The precipitate doesn't dissolve in an excess of water, nor in concentrated HCl, nor
in about 50% H2SO4. Any idea what this gunk might be? The bottle cap was slightly loose when I received it (but wrapped with electrical tape) so I
assume it was exposed to air for at least a few years. I think the solution was originally HCl in water with the TiCl3 also dissolved.
I was suspecting that the precipitate might be TiO2 but I thought that should dissolve in concentrated HCl.
It's difficult to find information about this chemical (TiCl3) because it seems that many sources confuse it with TiCl4, a super corrosive liquid
which produces HCl fumes in air and reacts violently with water (I also have about 100mL of that from a previous acquisition so I am familiar with
it).
Any info is appreciated!
Thanks,
Sean
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j_sum1
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TiO2 sounds about right.
TiCl3 is not stable in aqueous solution and even in strong solutions of HCl it will hydrolyse over a matter of days if not hours.
OTOH, TiO2 is pretty impervious to HCl and will sit happily, doing nothing in the bottom of a container.
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sbreheny
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Quote: Originally posted by j_sum1  | TiO2 sounds about right.
TiCl3 is not stable in aqueous solution and even in strong solutions of HCl it will hydrolyse over a matter of days if not hours.
OTOH, TiO2 is pretty impervious to HCl and will sit happily, doing nothing in the bottom of a container. |
Hmmm, well this was originally sold as a lab reagent so it must have had a shelf life of longer than days. I've attached a photo of the original
label. This label just says "20% solution" but almost every other source I can find states that there is about 30% HCl in the solution rather than
just water. Some of them also include phosphoric acid in about 3 to 5% concentration.
Can you think of any way to test whether this is indeed TiO2?
Sean
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j_sum1
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My experience with TiCl3 is from preparing it by reacting Ti powder with HCl. It won't have nearly the purity of proper reagent grade; it will have
impurities, more exposure to oxygen and is likely to degrade a lot quicker.
AFAIK TiO2 is the stable form that titanium nearly always ends up as. I don't recall what hydroxides are possible, but really, what else could it be?
As for tests for TiO2, I am not sure there are any simple ones. Keen to know if someone does have one.
This probably means your reagent is ruined. TiO2 is really inert and not worth much.
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