Which one of the following has the highest dipole moment? (i) CH2Cl2 (ii) CHCl3 (iii) CCl4

(i) Dichlormethane (CH2Cl2) μ = 1.60D (ii) Chloroform (CHCl3) μ = 1.08D (iii) Carbon tetrachloride (CCl4) μ = 0D CCl4 is a symmetrical molecule. Therefore, the dipole moments of all four C−Cl bonds cancel each other. Hence, its resultant dipole moment is zero. As shown in the above figure, in CHCl3, the resultant of dipole moments of two C−Cl bonds is opposed by the resultant of dipole moments of one C−H bond and one C−Cl bond. Since the resultant of one C−H bond and one C−Cl bond dipole moments is smaller than two C−Cl bonds, the opposition is to a small extent. As a result, CHCl3 has a small dipole moment of 1.08 D. On the other hand, in case of CH2Cl2, the resultant of the dipole moments of two C−Cl bonds is strengthened by the resultant of the dipole moments of two C−H bonds. As a result, CH2Cl2 has a higher dipole moment of 1.60 D than CHCl3 i.e., CH2Cl2 has the highest dipole moment. Hence, the given compounds can be arranged in the increasing order of their dipole moments as: CCl4 < CHCl3 < CH2Cl2 read less