Chapter 14, Problem 4STP

Interpretation Introduction

Interpretation: The quantity that decreases as intermolecular forces increases needs to be determined.

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.

Intermolecular forces effects boiling point, melting point, vapor pressure and surface tension.

Answer to Problem 4STP

Option “C” is correct.

Explanation of Solution

Vapor pressure can be defined as pressure exerted by vapor in equilibrium with its liquid state.

A molecule with higher intermolecular forces will be held tightly. Hence, fewer molecules will have sufficient kinetic energy to escape from the solution to the vapor state. Hence with increase in intermolecular forces vapor pressure will decrease.

Conclusion

With increase in intermolecular forces molecules becomes more associated and hence greater amount of energy required to separate them. As a result boiling point and melting point increases.

Surface tension can be defined as the force that acts on the surface of the liquid. Stronger the intermolecular forces between molecules greater the surface tension.