Arrange the following aromatic compounds in the correct increasing order of their dipole moments: To — Chemical Bonding Chemistry Question

💡 Solution & Explanation

$p$ -dichlorobenzene (IV) has symmetrical opposite dipoles ($\theta = 180^\circ$) giving $\mu = 0$. Toluene (I) has a small dipole due to the methyl group ($\approx 0.36\text{ D}$). For $m$ -dichlorobenzene (III, $\theta = 120^\circ$) and $o$ -dichlorobenzene (II, $\theta = 60^\circ$), the resultant dipole increases as the angle decreases ($\mu = \sqrt{\mu_1^2 + \mu_2^2 + 2\mu_1\mu_2\cos\theta}$). Hence, $IV < I < III < II$.