Question

$H_3{BO}_3$ is:

• A. monobasic and weak Lewis acid
• B. monobasic and weak Bronsted acid
• C. monobasic and strong Lewis acid
• D. tribasic and weak Bronsted acid

Answer 1

The correct option is A monobasic and weak Lewis acid

$H_{3}B{O}_3$ is known as boric acid. Any acid is defined as mono basic or dibasic or tribasic depending upon its capacity of giving $H^{+}$ ion.

$H_{3}B{O}_3$ accepts $O{H}^{-}$ ion to act as weak monobasic Lewis acid.

$H_{3}B{O}_3+H_{2}O\to B(OH{)}_4^{-}+H^{+}$

Water splits into $O{H}^{-}$ and $H^{+}$. $O{H}^{-}$ bonds with $B(OH{)}_3$ forming $B(OH{)}_4^{-}$ while $H^{+}$ ion is released in the solution.

The most important thing is that the $H^{+}$ ion comes from water, and not $B(OH{)}_3$.

Since only one $H^{+}$ can be released by a water molecule, boric acid is a monobasic acid.

Option A is correct.