Question

Out of $CCl_{4}$ and $SiCl_{4}$ which one reacts with water?

Answer 1

"Among ${ CCl }_{ 4 }$ and ${ SiCl }_{ 4 }$, the later will react with water. ${ CCl }_{ 4 }$ is a nonpolar covalent compound which will form the lower layer when added to water. This un-reactive nature is due to the size of carbon and chlorine. The bigger size of the chlorine atoms prevents the lone pair of oxygen in water molecule attacking the smaller carbon atom. Also, the lone pair of electrons is in need of an empty orbital to occupy. It is not available in the case of carbon.

In the case of ${ SiCl }_{ { 4 }^{ - } }$, Si atom is bigger and has available 3d vacant orbitals for the lone pair to occupy. Hence, before Si-Cl bond breaks oxygen atom is able to bond with silicon and the whole process is energetically favoured. Hence, the following reaction takes place.

${ SiCl }_{ 4 }\quad +\quad 2{ H }_{ 2 }O\quad \rightarrow \quad { SiO }_{ 2 }\quad +\quad 4HCl$"