Question

Dipole moment of methyl chloride is greater than chloroform

Answer 1

Let us consider C−Cl bond moment to be x and that of C−H bond to be y.

In CCl4, the dipole moment of any three C−Cl atoms is balanced by the dipole moment of the fourth C−Cl bond dipole moment. This means the resultant of dipole moment of three C−Cl bonds in tetrahedral structure is equal to x, which is equal and opposite to the dipole moment x of the fourth C−Cl bond.

Now, when we replace one of the chlorines with a hydrogen, the net dipole moment equals x+y, (as they are in the same directions). Similarly if we carry out the same procedure for CH3Cl it can be proved that its dipole moment is also x+y.