The gaseous potassium chloride molecule has a measured dipole moment or 10.0 D, which indicate that it is a very polar molecule. The separation between the nuclei in this molecule is $2.67\times {10}^{-8}\mathrm{cm}$. Calculate the percentage ionic character in KCI molecule.

Given,

${\mu }_{\text{observed }}=10\mathrm{D}$

Given compound  $\mathrm{KCl}$ to be 100% ionic charge on each atom,

$=4.8\times {10}^{-10}\mathrm{esu}$

$\therefore$Dipole moment in theory,

${\mu }_{\text{theoretical }}=\left(4.8\times {10}^{-10}\mathrm{esu}\right)\left(2.67\times {10}^{-8}\mathrm{cm}\right)$

${\mu }_{\text{theoretical }}=12.8\times {10}^{-18}\text{ esu.cm }=12.8\mathrm{D}$

The percentage ionic character is,

$\therefore \mathrm{\%}\text{ ionic character }=\frac{{\mu }_{\text{observed }}}{{\mu }_{\text{theoretical }}}\times 100=\frac{10}{12.8}\times 100\mathrm{\%}=78.125\mathrm{\%}$

As a result, %  ionic character $=78.125\mathrm{\%}$