(i) Discuss the significance/ applications of dipole moment.

(ii) Represent diagrammatically the bond moments and the resultant dipole moment in CO2 , NF3 and CHCl3.


(i) Dipole moment plays a very important role in understanding the nature of the chemical bonds.


A few applications are given below:


(1) Distinction between, polar and non-polar molecules. The measurement of the dipole moment can help us to distinguish between polar and non-polar molecules. Non-polar molecules have zero dipole moment while polar molecules have some value of dipole moment.


(2) Degree of polarity in a molecule. Dipole moment measurement also gives an idea about the degree of polarity, especially in a diatomic molecule. The greater the dipole moment, the greater is the polarity in such a molecule.


(3) The shape of molecules. In the case of molecules containing more than two atoms, the dipole moment not only depends upon the individual dipole moments of the bonds but also on the arrangement of bonds. Thus, the dipole moment is used to find the shapes of molecules.


(4) Distinguish between cis- and trans- isomers. Dipole moment measurements help to distinguish between cis- and trans- isomers because ds-isomer has usually higher dipole moment than trans isomer.


(5) Distinguish between ortho, meta and para isomers. Dipole moment measurements help to distinguish between o-, m- and p-isomers because the dipole moment of p-isomer is zero and that of o-isomers is more than that of m-isomer.


(ii) The diagrammatical representation of bond moments and the resultant dipole moment in CO2, NF3, and CHCl3 are:



NF3


CHCl3


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