Question

The dipole moment of chlorobenzene is $1.5D$. Calculate dipole moment of $1,2,3,5$-tetrachlorobenzene :

• A. $2.86D$
• B. $2.25D$
• C. $1.5D$
• D. $0D$

Answer 1

Answer: (C)

$1.5D$

Dipole moments of $2Cl$ and $5Cl$ are vectorially cancelled.

The dipole moment is due to $1Cl$ and $3Cl$.

$\mu ={\mu }_1^2+{\mu }_2^2+2{\mu }_1{\mu }_{2}cos\theta$

$=(1.5{)}^2\times (1.5{)}^2+2\times 1.5\times 1.5cos120$

$\therefore \mu =1.5D$

Therefore, option C is correct.