Place the following in order of decreasing dipole moment.
I.cis-CHCl=CHCl
II.trans-CHCl=CHCI
III.cis-CHF=CHF
A)III I II
B)II I III
C)I III II
D)II III I
E)I = III II

Question

Place the following in order of decreasing dipole moment.
I.cis-CHCl=CHCl 
II.trans-CHCl=CHCI 
III.cis-CHF=CHF
A)III > I > II
B)II > I > III
C)I > III > II
D)II > III > I
E)I = III > II

Quizplus · Accepted Answer

Dipole moment is directly proportional to electronegativity difference between two atoms and distance between them. Here, we have two factors for determining the dipole moment: Electronegativity difference and symmetrical vs asymmetrical placement of atoms.

In cis-CHCl=CHCl and cis-CHF=CHF, the atoms are placed symmetrical to each other, resulting in the highest dipole moment. Hence, III > I.

In trans-CHCl=CHCI, the atoms are placed symmetrically but the electronegativity difference between Cl and I is less than that of Cl and F. Hence, II has a lower dipole moment than I.

Therefore, the order of decreasing dipole moment is III > I > II.

Place the Following in Order of Decreasing Dipole Moment