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Author: Subject: a Titanium salt?
YT2095
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[*] posted on 20-6-2007 at 01:52
a Titanium salt?


this is a mystery for me, I made a titanium salt and have no idea what it is, I`ve tried searching different Ti salts and non match this stuff?

Dissolve Ti metal in Dil HCl (this takes a few days) it will be a deep purple color not too disimilar to KMnO4 soln.

next add H2O2, I used 9% soln and an equal part by volume.
this will get Quite hot and the liquid will turn blood red, so if you have stronger H2O2 adding a little at a time may be advisable.

allow this to cool again and then pour it out into a glass petri dish or watch glass, or any suitable evaporation dish.

the excess H2O2 and HCl will decompose and be driven off respectively leaving light lemon yellow crystals behind.

does anyone have any idea what they are?




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[*] posted on 20-6-2007 at 02:14


Welcome to the world of peroxo complexes. The blood-red material is a peroxo complex of titanium(IV).

First, when you add a small amount of H2O2, the purple titanium(III) is converted to colorless titanium(IV), which remains in strongly acidic solution as a hydroxy-titanyl complex, something like [TiO(OH2)5](2+), or [Ti(OH)2(OH2)4](2+). When more hydrogen peroxide is added, then the hydroxo ligands and possibly a water ligand as well, are replaced by a peroxo ligand.

On evaporation, most of this peroxo complex decomposes and what remains behind is hydrous TiO2, or some basic titanium(IV)chloride. The lemon yellow color is due to remains of the peroxo complex.




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[*] posted on 20-6-2007 at 03:37


I figured a peroxo, and tried an RP test with it, absolutely no reaction at all, I couldn`t make it do anything?

that includes setting it on fire and bashing it with a hammer, nothing.

I`ve seen and used Titanium dioxide before it`s a pure white powder we used to add a scoop to nylon pellets and tumble them before injection molding, these are definitely Crystals and quite transparent when seen under a microscope.
perhaps when pulverised they go pure white?




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[*] posted on 20-6-2007 at 03:53


If they are crystals, then I think more in the direction of some basic chloride. Try adding some of the crystals to water. Do they make the solution milky, or do they simply sink to the bottom, without impairing any turbidity to the water?

I also did not expect any action on RP. If the crystals are yellow, then the concentration of peroxo-complex in the crystals will be very low, probably only trace amounts. If this were a pure peroxo complex, then you would get a very energetic reaction with RP (you may remember my peroxochromate experiments with explosions and extreme sensitivity to friction).




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[*] posted on 20-6-2007 at 04:20


I just did that, and they sink and there`s a Slight turbidity, it also tests as Very acidic with litmus paper.

I added a flake of KOH, then it went Very turbid, but still most of the crystals at the bottom did not dissolve.

I then added more H2O2 and the liquid went clear and yellow and the crystals went Very Yellow, almost Picric yellow, gas is also coming off the crystals, there`s no noticable smell either.

aha, and the addition of Further H2O2 dissolves the crystals in the blink of an eye, I didn`t even see them vanish!?


[Edited on 20-6-2007 by YT2095]




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[*] posted on 20-6-2007 at 04:23


The Ti peroxo complex are not very stable, I doubt you could get much if any as a solid.

TiO2 is white when powdered, partially because of its high refractive index. In massive form (rutile) it is a pale yellow transparent material, good quality crystals have been used as gemstones (tradename Titania) but their softness limits that use.
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[*] posted on 20-6-2007 at 04:33


now That`s interesting!

"a pale Yellow" that`s how I would describe these also, but I`m sure it shouldn`t be Acidic in water, and certainly not Strongly acidic.

I`m beginning to think there may be more than just One compound present here.




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[*] posted on 20-6-2007 at 05:40


Got to correct myself - it is possible to crystallise out a hydrated mono-peroxide of titanium, effectively TiO3 . 2 H2O. It appears to be closer to the hydrated alkali and alkaline earth peroxides, or even the peroxided hydroxides, than the sort you're thinking of. Given the hydration it might not give energetic reactions unless the amounts were large enough to allow heat to build up.

There are also mixed salts such as Na2[TiO5].3 H2O and K4[TiO8].6 H2O when using concentrated H2O2. The reference is old, there may be new formulas for those.

Traces of the peroxide show up as pale yellow, deepening as the concentration of peroxide increases. So the yellow tint could be coming from that, as suggested earlier, or from other sources. An interesting test would be to take some of the yellow solid, put it in distilled water, and boil it for awhile.

As suggested, you could have a hydrated, perhaps basic, chloride, or just a lot of absorbed HCl.
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[*] posted on 20-6-2007 at 06:02


well this can`t be a mixed salt, it`s only ever seen Ti metal, as for the Acidity, perhaps absorbed HCl? I don`t know, you could be right, but the tiny amount I added to the de-ionised water the litmus indicator reaction was far too extreme for trace absorbtion.

although I will try and "Roast" some in test tube and see how much water condensation I get up the tube, and then the remaining color and properties of the crystals.
I`ll test the Ph of the condensation too, if it`s acidic then that should be revealing too.

it can only be a Chlorine based acid anyway.

[Edited on 20-6-2007 by YT2095]




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[*] posted on 20-6-2007 at 14:23


Peroxo-Ti is extremely stable in solution; I have some (in HCl) that's been sitting around for months and remains as red as the day I made it. I'm not very suprised it doesn't like making a stable salt, though.

For sure, the color is extremely strong. If it were pure peroxotitanium chloride, it would be like dried blood in color, much as a bright orange dichromate solution becomes translucent to opaque red-orange potassium dichromate crystals (I love that stuff!).

Tim




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