Question

The product formed in the reaction is $BC{{l}_{3}}+{{H}_{2}}O\to product:$
A.${{H}_{2}}B{{O}_{3}}+HCl$
B.${{B}_{2}}{{O}_{3}}+HOCl$
C.${{B}_{2}}{{H}_{6}}+HCl$
D.No reaction

Answer 1

Hint: 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 3 chlorine atoms by 3 sigma bonds. Also, there is no lone pair of electrons present on the central atom.

Complete answer:
Boron trichloride acts as a Lewis base. In the structure of boron trichloride there are 6 electrons present in the valence shell of the boron atom. The central boron atom is bonded with 3 chlorine atom with sigma bond.Before solving this question, lets 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 mentioned below:
\[BC{{l}_{3}}+3{{H}_{2}}O\to {{H}_{3}}B{{O}_{3}}+3HCl\]
If boron trichloride reacts with excess of water in the presence of sodium hydroxide the product formed is $Na[B{{(OH)}_{4}}]$ along with sodium chloride. The reaction involved is mentioned below:
\[BC{{l}_{3}}+{{H}_{2}}O+NaOH\to Na[B{{(OH)}_{4}}]+NaCl\]
The balanced chemical reaction involved is mentioned below:
\[2BC{{l}_{3}}+3{{H}_{2}}O+2NaOH\to Na[B{{(OH)}_{4}}]+NaCl\]

Hence, the correct answer is option (A).

Note:
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.