Ncert Exercises & Solutions

Draw the structure of boric acid shown hydrogen bonding. Which species is present in water? What is the hybridisation of boron in this species?

Orthoboric acid H₃BO₃, in solid state possesses a layer structure made up of

B {(OH)}_{3}

units forming hexagonal rings of H-bonding as given below

Each H-atom acts as a bridge between two oxygen atoms of different

{BO}_{3}^{3 -}

units.

Boric acid when dissolved in water, act as Lewis acid forming

B {(OH)}_{4}^{-}

H_{3} {BO}_{3} + H_{2} O \to B {(OH)}_{4}^{-} + H^{+}

The hybridisation of boron in

B {(OH)}_{4}^{-}

is sp³.