Question
Which of the following statements about $${H_3}B{O_3}$$ is not correct?
A.
It is a strong tribasic acid
B.
It is prepared by acidifying an aqueous solution of borax
C.
It has a layer structure in which planar $$B{O_3}$$ units are joined by hydrogen bonds
D.
It does not act as proton donor but acts as a Lewis acid by accepting hydroxyl ion
Answer :
It is a strong tribasic acid
Solution :
Boric acid $$\left( {{H_3}B{O_3}} \right)$$ is a weak monobasic acid with $${K_a} = 1.0 \times {10^{ - 9}}.$$ It may be noted that boric acid does not act as a protonic acid ( i.e. proton donor ) but behaves as a Lewis acid by accepting a pair of electrons from $$O{H^ - }$$ $$ion.$$
$$B{\left( {OH} \right)_3} + 2H - O - H \to $$ $${\left[ {B{{\left( {OH} \right)}_4}} \right]^ - } + {H_3}{O^ + }$$