Question

If dipole moment of chlorobenzene is $1.5$ D, then what is the sum of magnitude of dipole moment of all the benzenoid form of $C_6{H}_{4}C{l}_2$?

• A. $2.6$ D
• B. $4.1$ D
• C. $1.5$ D
• D. $2.05$ D

Answer 1

The correct option is B $4.1$ D

The possible benzenoid structures of $C_6{H}_{4}C{l}_2$ are as follow:

As we know, $\mu =\sqrt{{\mu }_1^2+{\mu }_2^2+2{\mu }_1{\mu }_{2}cos\theta }$
(I) $\mu =\sqrt{{1.5}^2+{1.5}^2+2\times {1.5}^{2}cos{60}^o}\approx 2.6D$

(II) $\mu =\sqrt{{1.5}^2+{1.5}^2+2\times {1.5}^{2}cos{120}^o}=1.5D$

(III) Dipole moment vectors cancle out each other giving net dipole as zero.

Hence total sum becomes $4.1$ D.