Chapter 12, Problem 13A

Interpretation Introduction

Interpretation:

The term dipole moment is to be defined giving examples.

Concept introduction:

A covalent bond that is formed by two different atoms is polar in nature and its polarity is numerically calculated using dipole moment.

Answer to Problem 13A

The dipole moment of a bond is defined as a product of the charge carried by an atom multiplied by the distance between the charges.

Let’s consider a bond $\mathrm{A}-\mathrm{B}$ having charge $\partial +\mathrm{a}\mathrm{n}\mathrm{d}\partial -$ with $\mathrm{r}$ distance apart, the dipole moment is given by:

  $\mathrm{d}\mathrm{i}\mathrm{p}\mathrm{o}\mathrm{l}\mathrm{e}\mathrm{m}\mathrm{o}\mathrm{m}\mathrm{e}\mathrm{n}\mathrm{t}=\mathrm{q}\times \mathrm{r}$

The units of dipole moment are $\mathrm{e}\mathrm{s}\mathrm{u}-\mathrm{c}\mathrm{m}\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{D}\mathrm{e}\mathrm{b}\mathrm{y}\mathrm{e}(\mathrm{D})$

The molecules possessing dipole moment are:

Black arrows are dipole moments of bonds and purple arrows show overall dipole moment of molecules.

Explanation of Solution

A molecule possesses a dipole moment if the resultant of all dipoles give some value of dipole moment.

For example: $\mathrm{H}\mathrm{C}\mathrm{l},\mathrm{C}\mathrm{H}\mathrm{C}{\mathrm{l}}_3$

Conclusion

Thus, the dipole moment gives the measurement of polarity in a molecule.