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 1

The correct option is A It is a strong tribasic acid

$H_{3}B{O}_3$ is not a tribasic acid.
Aqueous solution, instead of donating the $-OH$ group it breaks the $H-OH$ bond of water and accepts the $-OH$ group from it leaving in the solution hence it is monobasic acid.
$B(OH{)}_3+H_{2}O\to [B(OH{)}_4{]}^{-}+H^{+}$
It has a layer structure in which planar $B{O}_3$ units are joined by hydrogen bonds.
It does not act as proton donor but acts as a Lewis acid by accepting hydroxyl ion.
Prepration by Borax - Boric acid is prepared by reaction of borax with mineral acid (or hydrochloric acid). Reaction involved is given below –

$N{a}_2{B}_4{O}_7.10H_{2}O+2HCl\to 4B(OH{)}_3+2NaCl+5H_{2}O$