dipole moment of CHCl3 is less than CH2Cl2 is less than CH3Cl. why?

Question

anonymous · Answer

CH2Cl2 has the greatest dipole moment. CCl4 is the only one without a dipole. 
The electronegativity difference in the two atoms causes a polar bond which results in a partial charge on each atom. 
These molecules are in a tetrahedral configuration, so the two Cl atoms in CH2CL2 do not cancel out, they are additive. These charges act like vectors when in a magnetic field. Think of the geometry or build a model of the molecule and you will see why CHCl3 results in a lower net dipole than CHCl2

yash2651995 · Answer

CH3Cl has maximum dipole (1.87 D) in case of polyatomic molecules(4 atoms one).
is how 2 are additive and 3 isnt? all three are at 109.5 degrees from each other one component should add up isnt it?? and CCl4 will be 0 dipole agreed.. 

resultant of 2 dipoles:
Ures=Sqrt(u^2+u^2+u x u x cos (109.5))
 =sqrt(u^2(2+cos(109.5)))= u sqrt(2-2*0.325) = u (1.16)
which is greater than u ie dipole of one.. 

so it is additive in case of 2 and even additive in case of three
Ures=u(1.694)
(warning: maths work could be wrong)

then, how can this (what is mentioned in question) happen..

anonymous · Answer

CH3Cl has greater dipole moment than CH2Cl2 because of symmetry of molecule:
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