Chapter 14, Problem 57A

Interpretation Introduction

Interpretation: The comparison of dipole-dipole attraction between two molecules and a covalent bond between two atoms is to be described.

Concept introduction: The forces of attraction between the molecules of a substance (solid, liquid or gaseous) are called intermolecular forces or Vanderwaal’s forces.

Answer to Problem 57A

Dipole-dipole Interactions: This type of force of attraction is present among the molecule having permanent dipoles i.e. polar molecules. The positive pole of one molecule is thus attracted by the negative pole of the other molecule.

Covalent Bond: A covalent bond may be defined as the bond formed by mutual sharing of electrons between the combining atoms of comparable electronegativity.

Explanation of Solution

Dipole-dipole attraction is in between two polar molecules such as $HF$ and $HCl$ . The polarities of the molecules predict the magnitude of dipole-dipole forces in different polar molecules, which depends upon the electronegativities of the atoms and the geometry of the molecule.

In $HF$ and $HCl$ molecules, as the bonds involved in the overlap are different, the extent of overlap is different and hence the strength is different. Therefore, the relative strength of bonds is as follows:

Covalent bond>Dipole-dipole interaction

Conclusion

The polar covalent bond is stronger than the dipole-dipole interaction on the basis of intra and intermolecular forces present between them.