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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: xshadow on October 10, 2020, 04:29:01 AM

Title: TICl4 in HCl (15%) + NH3 excess
Post by: xshadow on October 10, 2020, 04:29:01 AM
I'll have to do this mini- experiment:
TiCl4 in HCl (15%) ,than I add NH3 in excess

The reaction should be:

NH3 + HCl  ----> NH4+ + Cl-
NH3 is in excess.
So in the solution I'll have OH- (basic pH) ,some NH3 ,some Cl- and TiCl4


Now different things I think they may happen:

1) TiCl4 + 2OH-  ---> [ TiCl4OH2 ] 2-  ( I think Titanium can do exacohordinated complex)
2)TiCl4 + 2OH- ----> Ti(OH)4  (ligand excanche)
3)Ti(OH)4  + 2 OH- ----> Ti(OH)6  2-


a) Now I  check and I found that the 2) happens.... formation of the complex TI(OH)4  (is a complex??...or a ionic compound??!) and then precipitation
Why  the 1) and 2) can't occour----- ???

b) in a solution of TiCl4 in HCl (15%) I have only TiCl4...or I have also some TI4+ free (complexation equilibrium)

thanks
Title: Re: TICl4 in HCl (15%) + NH3 excess
Post by: chenbeier on October 10, 2020, 07:18:34 AM
TiCl4 will react with water or hydoxide directly to TiO2,  nothing between will be get.
Its getting big white nebula fumes.
Title: Re: TICl4 in HCl (15%) + NH3 excess
Post by: AWK on October 10, 2020, 08:15:23 AM
I guess you don't understand what an optimized chemical procedure means.
If you have read the recommended 3 pages of the Brauer texbook, his procedure use slightly dilute hydrochloric acid (approx. 33%), temperature of 0°C, ammonium chloride, titanium tetrachloride, and then the solution is saturated with gaseous hydrogen chloride to precipitate yellow ammonium hexachlorotitanate (note - the compound is only stable in the presence of very concentrated hydrochloric acid and only with saturated HCl the solution this compound precipitates). Attempting to dry the compound decomposes it. Hydrolysis occurs at lower concentrations of hydrochloric acid (temporarily with the formation compound with Ti-O-Ti bond) or leads to complete hydrolysis.
Title: Re: TICl4 in HCl (15%) + NH3 excess
Post by: xshadow on October 10, 2020, 08:22:00 AM
Quote from: AWK on October 10, 2020, 08:15:23 AM
I guess you don't understand what an optimized chemical procedure means.
If you have read the recommended 3 pages of the Brauer texbook, his procedure use slightly dilute hydrochloric acid (approx. 33%), temperature of 0°C, ammonium chloride, titanium tetrachloride, and then the solution is saturated with gaseous hydrogen chloride to precipitate yellow ammonium hexachlorotitanate (note - the compound is only stable in the presence of very concentrated hydrochloric acid and only with saturated HCl the solution this compound precipitates). Attempting to dry the compound decomposes it. Hydrolysis occurs at lower concentrations of hydrochloric acid (temporarily with the formation compound with Ti-O-Ti bond) or leads to complete hydrolysis.

My slides say that   there will be the precipitation of Ti(OH)4 using HCl + NH3 in excess..

but I don't understand why is formed Ti(OH)4 and not for example  TiCl4(OH)2 ^2-   or Ti(OH)6 ^2- ecc
Don't find any logic ...logic that I found in organic chemistry  ??? ???

Title: Re: TICl4 in HCl (15%) + NH3 excess
Post by: AWK on October 10, 2020, 09:28:41 AM
The product of the hydrolysis with ammonia will likely be hydrated titanium oxide. It can be completely dehydrated at temperatures over 300°C.
Title: Re: TICl4 in HCl (15%) + NH3 excess
Post by: xshadow on October 10, 2020, 04:56:39 PM
Quote from: AWK on October 10, 2020, 09:28:41 AM
The product of the hydrolysis with ammonia will likely be hydrated titanium oxide. It can be completely dehydrated at temperatures over 300°C.

Thanks!