Question

$MC{l}_4\underset{Zn}{\overset{heat}{\to }}$ Purple colour compound (Colourless (A)
liquid)
$M=$ Transition metal
$\downarrow Moist$ air
(B)
White fumes
Identify (A), (B) and $MC{l}_4$. Also explain colour difference between $MC{l}_4$ and (A).

Answer 1

$Ti{Cl}_4\underset{Zn}{\overset{heat}{\to }}Ti{Cl}_3\underset{H_{2}O}{\overset{}{\to }}\left[Ti{\left(H_{2}O\right)}_6\right]{Cl}_3$ Purple color (A)
$Ti{Cl}_4+(n+2)H_{2}O$ (moist air)$⟶Ti{O}_2{\left(H_{2}O\right)}_n+4HCl\uparrow$ white fumes (B)
${Ti}^{4+}=\left[Ar\right]3d°$
${Ti}^{3+}=\left[Ar\right]3d^1$
Ti (+IV) ion contains no d-electron, while d-d-transition of single electron in Ti (+III) causes color change.