Chapter 14, Problem 1A

Interpretation Introduction

Interpretation: The dipole-dipole attraction with three examples of liquid substances which possess high dipole-dipole attraction needs to be explained.

Concept introduction: Molecules are held together by forces, sometimes called inter

molecular forces, that exist between the molecules.

There are mainly three kinds of intra-molecular forces,

• Dipole-dipole attraction.
• Hydrogen bond.
• London dispersion force.

Answer to Problem 1A

Dipole-dipole attraction occurs between polar molecules. Three examples of liquid organic substances having high dipole-dipole attraction are acetone ( $C{H}_{3}COC{H}_3$ ), acetonitrile ( $C{H}_{3}CN$ ), and acetaldehyde ( $C{H}_{3}CHO$ ).

Explanation of Solution

When polar molecules with dipole moments are put together, they orient themselves in such a way that molecules having dipole moments can get attracted to each other in such a way that the positive and negative portion of the molecules are close to each other.

For example, in acetone due to electronegativity difference between carbon and oxygen, a dipole moment is generated where oxygen acquires partial negative charge and carbon acquires partial positive charge. So, negative end of oxygen of one acetone molecule is attracted towards positive end of carbon of another molecule of acetone.

Conclusion

Dipole-dipole attraction occurs between polar molecules. Three examples of liquid substances having high dipole-dipole attraction are acetone ( $C{H}_{3}COC{H}_3$ ), acetonitrile ( $C{H}_{3}CN$ ), and acetaldehyde ( $C{H}_{3}CHO$ ).