Question

In the reaction, ${{I}_{2}}+{{I}^{-}}\xrightarrow{{}}{{I}_{3}}^{-}$the Lewis base is
a.) ${{I}_{2}}$
b.) ${{I}^{-}}$
c.) ${{I}_{3}}^{-}$
d.) None

Answer 1

Hint: In order to answer this question, we have to know the meaning of Lewis base and its characteristics. The contribution of a Lewis base in case of a chemical reaction, gives us an idea about which one can be the Lewis base, in the chemical reaction mentioned in the question. The concept of electron donating species and electron accepting species should also be clear. This is because the answer is based total on the concept of electron donation in a chemical reaction.

Complete step by step solution:
 A Lewis base, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis Acid to form a Lewis adduct.
In the above equation, we can see that ${{I}^{-}}$can act as a Lewis base. This is because in the following equation: ${{I}_{2}}+{{I}^{-}}\xrightarrow{{}}{{I}_{3}}^{-}$, it donated the pair of electrons to some other species. So, this electron donor species is called a Lewis base.

Hence, the correct answer is Option B.

Additional Information: A Lewis acid is any substance which can accept a pair of non-bonding electrons. In other words, we can say that Lewis acid is an electron pair acceptor. On the other hand, we can say that Lewis base is an electron pair donor.

Note: From the concept of Lewis base mentioned in the question, we can say that Lewis bases are nucleophilic. This means that the Lewis bases attack a positive charge with their lone pair. They also utilize the highest occupied molecular orbital. An atom, ion, or molecule with a lone pair of electrons can thus be a Lewis base.