Question #62993

1 Answer
Feb 21, 2016

Answer:

Yes, we can.

Explanation:

You're dealing with the hydrolisis of boron trichloride, #"BCl"_3#.

This reaction will produce boric acid, which you'll see written both as #"H"_3"BO"_3# and as #"B"("OH")_3#, and hydrochloric acid, #"HCl"#.

The balanced chemical equation would indeed look like this

#"BCl"_text(3(aq]) + 3"H"_2"O"_text((l]) -> "B"("OH")_text(3(aq]) + 3"HCl"_text((aq])#

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 #"sp"^2# hybridized, has an empty 2p-orbital.

http://www.tutorvista.com/content/chemistry/chemistry-iv/p-block-elements/reactivity-elements.php

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 #["H"_2"O"-"BCl"_3]^(-)#, is formed, a hydrogen atom located on the water molecule will jump off, leaving an #"OH"-# group attached to the boron trichloride.

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

http://npic.orst.edu/factsheets/archive/borictech.html

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

#"B"("OH")_text(3(aq]) + "H"_2"O"_text((l]) rightleftharpoons ["B"("OH")_text(4(aq])]^(-) + "H"_text((aq])^(+)#