Question

Which of the following statements about $H_3BO_3$ 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 $BO_3$ 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 1

Answer: (A)

Boric acid $(H_3BO_3)$ 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 $OH^-$ ion. $B(OH)_33 + 2H - O - H \longrightarrow [B(0H)_4]^- + H_3O^+$