# Question 62993

Feb 21, 2016

Yes, we can.

#### Explanation:

You're dealing with the hydrolisis of boron trichloride, ${\text{BCl}}_{3}$.

This reaction will produce boric acid, which you'll see written both as ${\text{H"_3"BO}}_{3}$ and as "B"("OH")_3, and hydrochloric acid, $\text{HCl}$.

The balanced chemical equation would indeed look like this

${\text{BCl"_text(3(aq]) + 3"H"_2"O"_text((l]) -> "B"("OH")_text(3(aq]) + 3"HCl}}_{\textrm{\left(a q\right]}}$

I'll try to explain what's going on here without going into too much detail. Mind you, this is a simplified version of what actually goes on, but it will give you an idea of how things work here.

The boron atom in boron trichloride, which is ${\text{sp}}^{2}$ hybridized, has an empty 2p-orbital.

This means that it can act as a Lewis acid, i.e .accept a pair of electrons from the oxygen atom of a water molecule.

This will lead to the formation of an adduct, which is simply the result of the addition of two molecules.

Once this adduct, which can be represented as ${\left[{\text{H"_2"O"-"BCl}}_{3}\right]}^{-}$, is formed, a hydrogen atom located on the water molecule will jump off, leaving an $\text{OH} -$ group attached to the boron trichloride.

This will trigger the replacement of the $\text{B"-"Cl}$ bonds with stronger $\text{B"-"O}$ bonds, resulting in the formation of boric acid, "B"("OH")_3.

As an interest follow-up, boric acid acts as an acid not because it donates protons, ${\text{H}}^{+}$, but because it pulls another $- \text{OH}$ group from water to form the tetrahydroxyborate anion, ["B"("OH")_4]^(-)#

${\text{B"("OH")_text(3(aq]) + "H"_2"O"_text((l]) rightleftharpoons ["B"("OH")_text(4(aq])]^(-) + "H}}_{\textrm{\left(a q\right]}}^{+}$