Question

Identify from the following list of molecules and ions which behave as Lewis acids: CO2, NH3, BCl3, Fe3+. (A) CO2 and NH3 (B) NH3 and BCl3 (C) CO2 and Fe3+ (D) CO2, BCl3, and Fe3+ (E) CO2, NH3, BCl3, and Fe3+

Answer 1

Answer : The correct option is, (D) CO₂, BCl₃, and Fe³⁺

Explanation :

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

(a) $CO_2$

It is a Lewis-acid because it can accepts electron pairs.

(b) $NH_3$

It is not a Lewis-acid because it can not accepts electron pairs but it is a base because it can donates and accept hydrogen ion.

(c) $BCl_3$

It is a Lewis-acid because it can accepts electron pairs because it has an incomplete octet and an empty 2p orbital.

(d) $Fe^{3+}$

It is a Lewis-acid because it can accepts electron pairs.

Hence, the ions which behave as Lewis acids are, CO₂, BCl₃, and Fe³⁺