Chapter 11, Problem 11.1P

Interpretation Introduction

Interpretation: The molecules that have dipole-dipole interactions out of given molecules are to be identified.

Concept introduction: Dipole-dipole interactions exist in polar molecules. Because of presence of opposite charges dipoles are created in polar molecules. The formation of dipoles results in dipole-dipole interactions.

To determine: The molecules that possess dipole-dipole interactions.

Correct answer: The correct options are (b) and (c).

Explanation of Solution

Reason for correct answer: The given molecule ${\text{CH}}_3\text{Cl}$is slightly polar in nature because there is less difference between electronegative value of carbon and hydrogen, whereas electronegative value of chlorine is more than that of carbon.

Thus, due to polarity of $\text{C}-\text{Cl}$bond, this molecule is slightly polar in nature and this molecule shows possibility of dipole-dipole interactions.

The given molecule $\text{HCl}$is polar in nature due to difference of electronegative value of of $\text{H}$and $\text{Cl}$atom. The electronegative value of $\text{H}$is $2.1$and electronegative value of $\text{Cl}$is $3.16$ .

Therefore, $\text{HCl}$shows dipole-dipole interactions.

Reason for incorrect options: The given molecule ${\text{CI}}_4$shows less difference between the electronegativity of both types of atoms present in this molecule. The electronegativity of carbon is $2.5$ , whereas the electronegativity of iodine is $2.6$ .

Due to less difference of electro-negativity, this molecule is non-polar.

Therefore, the given molecule does not possess dipole-dipole interactions.