Chemical Bonding and Molecular Structure

Choose the polar molecule from the following:

1. CCl4
2. CO2
3. CH2=CH2
4. CHCl3

Answer

(4) CHCl3

Solution

A molecule is non-polar (μ = 0) when its bond dipoles cancel by symmetry.

(A): CCl4 regular tetrahedral, four equal C–Cl dipoles cancel ⇒ (A) non-polar

(B): O=C=O linear, two opposite dipoles cancel ⇒ (B) non-polar

(C): CH2=CH2 planar and symmetrical ⇒ (C) non-polar

(D): CHCl3 one C–H and three C–Cl dipoles do not cancel ⇒ (D) polar

[figure]

Answer: (4)