Chapter 12, Problem 12.31QP

Interpretation Introduction

Interpretation:

The surface tension of ethanol and dimethyl ether has to be compared.

Concept Introduction:

Surface tension of the liquid refers to the attractive force between the liquid molecules in the bulk of the liquid and those molecules in the surface of the liquid.

In liquids, molecules in the bulk region are surrounded by each other to a very large extent than in the surface region.  So they have their intermolecular forces spread out to a very large extent among them and have lower energy.  But in the surface region, the sharing of this intermolecular force with their neighboring molecules is minimal so that the molecules remain in the surface region tends to have more energy.

Due to this, the molecules in the bulk region attempts to pull those molecules in the surface region by exerting force on them which is known as surface tension.  As a result, the surface area and surface energy of the molecules in the liquids are lowered.

Greater the strength of the intermolecular force in a substance, greater will be its surface tension.