Difference of dipole moments of dichloromethane and trichloromethane?

Question

Why is the dipole moment of $\\ce{CH2Cl2}$ ($1.60 ~\\mathrm{D}$) greater than that of $\\ce{CHCl3}$ ($1.08~\\mathrm{D}$)? Based on my knowledge of vectors, I feel it should be the other way around.

Answer 1

Dichloromethane has two polar bonds and two nonpolar bonds. Trichloromethane has three polar bonds and only one nonpolar bond. Because trichloromethane has less electron density in nonpolar bonds and more electron density in polar bonds, it has a larger dipole moment. Keep in mind this is only true because their polar bonds do not offset