Chemical Bonding and Molecular Structure — Chemistry STD 11 Science — Question
Gujarat BoardEnglish MediumSTD 11 ScienceChemistryChemical Bonding and Molecular Structure5 Marks
Question
Write the significance/applications of dipole moment.
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Answer
In heteronuclear molecules, polarization arises due to a difference in the electronegativities of the constituents of atoms. As a result, one end of the molecule acquires a positive charge while the other end becomes negative. Hence, a molecule is said to possess a dipole.
The product of the magnitude of the charge and the distance between the centres of positive-negative charges is called the dipole moment $(\mu)$ of the molecule. It is a vector quantity and is represented by an arrow with its tail at the positive centre and head pointing towards a negative centre.
Dipole moment $(\mu)=$ charge $(\mathrm{Q}) \times$ distance of separation $(r)$
The SI unit of a dipole moment is 'esu'.
1 esu $=3.335 \times 10^{-30} \mathrm{Cm}$
Dipole moment is the measure of the polarity of a bond. It is used to differentiate between polar and non-polar bonds since all non-polar molecules (e.g. $\mathrm{H}_2, \mathrm{O}_2$ ) have zero dipole moments. It is also helpful in calculating the percentage ionic character of a molecule.
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