Question

Which one of the following has the highest dipole moment ?

$C{H}_{2}C{l}_2$

$CHC{l}_3$

$CC{l}_4$

Answer 1

$CC{l}_4$ (tetrachloromethane) is a symmetrical molecule so, it has zero dipole moment.

In $CHC{l}_3$ (trichloromethane/chloroform,) the resultant of two C - Cl dipole moments is opposed by the resultant of C - H and C - Cl bond. Since, the latter resultant dipole moment is smaller than the former, $CHC{l}_3$ has a dipole moment = 1.03 D.

In $C{H}_{2}C{l}_2$ (dichloromethane), the resultant of two C - Cl dipole moments is reinforced by the resultant of two C-H bonds. Thus, $C{H}_{2}C{l}_2$ has a dipole moment = 1.62 D.

Therefore, $C{H}_{2}C{l}_2$ has the highest dipole moment amongst the above three molecules.

$CC{l}_4$ is also called carbon tetrachloride; $C{H}_{2}C{l}_2$ is methylene chloride.