Chapter 8, Problem 70A

Interpretation Introduction

Interpretation: The molecules which are least likely to form a hydrogen bond with a water molecule need to be identified.

Concept Introduction: A hydrogen bond is formed when a molecule with a hydrogen atom attached to an electronegative atom is near a molecule of the same and different kind having a hydrogen atom bonded to an electronegative atom.

Explanation of Solution

Reason for correct option/s:

The given molecule in option (b) is ${\text{CH}}_{\text{3}}\text{Cl}$ . Here, the electronegative Cl atom is not bonded to a hydrogen atom. Thus, it cannot form a hydrogen bond with a water molecule. Thus, ${\text{CH}}_{\text{3}}\text{Cl}$ is likely to form a bond with the water molecule.

Conclusion

Reason for incorrect option/s:

The given molecule in option (a) is ammonia. Here, nitrogen is an electronegative atom containing one lone pair. The hydrogen bond is formed when a molecule containing a hydrogen atom bonded with an electronegative atom show bonding with an electronegative atom bonded with the hydrogen atom in the same or different molecule. Here, a hydrogen atom bonded with an oxygen atom in a water molecule can form a hydrogen bond with ammonia.

Thus, ${\text{NH}}_{\text{3}}$ can form a hydrogen bond with a water molecule, and option (a) is incorrect.

The given molecule in option (c) is HF. Here, F is an electronegative atom bonded with the hydrogen atom. It can show hydrogen bonding with the water molecule.

The given molecule in option (d) is ${\text{H}}_{\text{2}}{\text{O}}_{\text{2}}$ . Here O is an electronegative atom bonded with hydrogen atoms. Thus, it can show hydrogen bonding with the water molecule.