• # question_answer20) Write the significance of dipole moment.

Dipole moment has large number of applications in determination and confirmation of molecular structure. Some of its important applications are given below: (1) If a molecule has zero dipole moment is said to be nonpolar or non-ionic. (2) Percentage ionic character of a bond can be calculated using following relation: Percentage of ionic character   =$\frac{\text{Experimental value of dipole moment}}{\text{Theoretical value of dipole moment}}$ (3) To determine geometry of molecules: The values of dipole moments provide valuable information about the structure of molecules. (a) $C{{O}_{2}},C{{S}_{2}}$ molecules are linear as values of their dipole moments are zero. (b) ${{H}_{2}}O$ is not a linear molecule as it has dipole moment. Actually, it has V-shaped structure and the bond angle is $105{}^\circ$. Similarly, $S{{O}_{2}}$ has a bent structure. (c) In ammonia, three hydrogen atoms do not lie symmetrically with respect to nitrogen as it has dipole moment. It has a pyramidal structure. (4) To determine orientation in benzene ring: Dipole moment is useful to ascertain the orientation of substituents. Greater the dipole moment, greater is the asymmetry. In general, dipole moment follows the order: Ortho > meta > para