Question

Which of the following molecules has the Maximum Dipole Moment?

• A. ${\mathrm{CO}}_2$
• B. ${\mathrm{CH}}_4$
• C. ${\mathrm{NH}}_3$
• D. ${\mathrm{NF}}_3$

Answer 1

The correct option is C

${\mathrm{NH}}_3$

Explanation for correct option:

C. ${\mathrm{NH}}_3$

Dipole moment:

• “Dipole moment is defined as the product of the magnitude of the charge and the distance between the centers of positive and negative charge”
• It is expressed as $\left(\mathrm{\mu }\right)$.
• The dipole moment will be higher in ${\mathrm{NH}}_3$ as in ammonia molecule, the orbital dipole due to the lone pair being in the same direction as the resultant dipole moment of the N – H bonds.
• The net dipole moment of ${\mathrm{NH}}_3$ is $4.90\times {10}^{-30}\mathrm{C}\mathrm{m}$.
• The structure of ${\mathrm{NH}}_3$is given below.

Explanation for incorrect options:

A. ${\mathrm{CO}}_2$

• It has zero dipole moment as the molecule is symmetrical, and the dipoles get canceled with each other.

B. ${\mathrm{CH}}_4$

• It has zero dipole moment as the dipoles get canceled with each other.

D. ${\mathrm{NF}}_3$

• "In ${\mathrm{NF}}_3$ the orbital dipole is in the direction opposite to the resultant dipole moment of the three N–F bonds. The orbital dipole because of lone pair decreases the effect of the resultant N – F bond moments."
• The net dipole moment of ${\mathrm{NF}}_3$ is $0.8\times {10}^{-30}\mathrm{C}\mathrm{m}$.
• The structure of ${\mathrm{NF}}_3$is given below.

Hence. the correct option is C i.e. ${\mathrm{NH}}_3$ has the highest dipole moment.