Question

Classify the following into Lewis acids and Lewis bases:
(a) $H_{2}O$
(b) $N{H}_3$
(c) $H^{+}$
(d) $B{F}_3$
(e) $AI{H}_3$
(f) $ROH$
(g) $C{H}_{3}N{H}_2$
(h) $C{N}^{-}$
(i) ${}^{+}C{H}_3$
Lewis acids : (c), (d), (e), (i)
Lewis bases : (a), (b), (f), (g), (h)
If true enter 1, else enter 0.

Answer 1

In the Lewis theory of acid-base reactions, bases donate pairs of electrons and acids accept pairs of electrons. A Lewis acid is therefore any substance, that can accept a pair of non-bonding electrons. In other words, a Lewis acid is an electron-pair acceptor. A Lewis base is any substance, that can donate a pair of non-bonding electrons. A Lewis base is therefore, an electron-pair donor.
So, (c), (d), (e), (i) are Lewis acids and (a), (b), (f), (g), (h) are Lewis bases.