Question

What are the species that are formed when ${\mathrm{BCl}}_3$ is hydrolyzed?

Answer 1

Trichlorides of Boron (${\mathrm{BCl}}_3$):

• The trichlorides of Boron are covalent in nature.

Hydrolysis of ${\mathrm{BCl}}_3$:

• When Boron trichloride $\left({\mathrm{BCl}}_3\right)$ is treated with water$\left({\mathrm{H}}_2\mathrm{O}\right)$, it gets hydrolyzed and forms$\left[\mathrm{B}{{\left(\mathrm{OH}\right)}_4}^{-}\right]$.
• $\left[\mathrm{B}{{\left(\mathrm{OH}\right)}_4}^{-}\right]$ is tetrahedral in structure and here is Boron is sp³ hybridized.
• The chemical reactions can be depicted as:

$$\begin{gathered} {\mathrm{BCl}}_3\left(\mathrm{g}\right)+3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to \mathrm{B}{\left(\mathrm{OH}\right)}_3\left(\mathrm{s}\right)+3\mathrm{HCl}\left(\mathrm{aq}\right) \\ \mathrm{Boric}\mathrm{acid} \\ \mathrm{B}{\left(\mathrm{OH}\right)}_3\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to \left[\mathrm{B}{{\left(\mathrm{OH}\right)}_4}^{-}\right]\left(\mathrm{aq}\right)+{\mathrm{H}}^{+}\left(\mathrm{aq}\right) \end{gathered}$$