Question

What are the species that are formed when $BC{{l}_{3}}$ is hydrolyzed?

Answer 1

Hint : We know that boron trichloride is a colourless gas which generally has a pungent odour. To understand the structure of boron trichloride is easy, boron is the central atom in the compound and it is bonded to three chlorine atoms by three sigma bonds. Also, there is no lone pair of electrons present on the central atom.

Complete Step By Step Answer:
Boron trichloride acts as a Lewis base. In the structure of boron trichloride there are six electrons present in the valence shell of the boron atom. The central boron atom is bonded with three chlorine atoms with a sigma bond. Before solving this question, let's understand some basic concepts: The reactivity of the $-OH$ group is higher than that of the $-Cl$ group. Hence water reacts with boron trichloride the $-OH$ substituents from water substitutes the $-Cl$ group in boron trichloride. The reaction involved is mentioned below:
$BC{{l}_{3}}+{{H}_{2}}O\to {{H}_{3}}B{{O}_{3}}+HCl$ The balanced chemical reaction involved Is given as; $BC{{l}_{3}}+3{{H}_{2}}O\to {{H}_{3}}B{{O}_{3}}+3HCl$

Additional Information:
The trichloride of group $~13$ being covalent in nature, form tetrahedral ${{\left[ M{{\left( OH \right)}_{4}} \right]}^{}},$ on hydrolysis in water. When $~BC{{l}_{3}}$ is treated with water, it hydrolyses and forms $\left[ B \right[OH{{\left] _{4} \right]}^{}}$ . The Boron in the $\left[ B \right[OH{{\left] _{4} \right]}^{~}}$ ion involves one $2s$ orbital and $3\text{ }2p$ orbitals.
Thus, the hybridization of the Boron atom is $s{{p}^{3}}.$

Note :
Remember that Boron trichloride is very reactive and it can be corrosive when it is bought in contact with metals. It is toxic for the tissue cells. When a human comes in contact with this gas, it can cause irritation in the eyes and sometimes even leads to mucous membranes.