6 Apr 2019

Difference Between Surface Energy And Surface Tension


People usually get confused that surface energy and surface tension are the same which is not true. In this article let us understand what is the difference between surface energy and surface tension.

Surface energy and surface tension are the measurements of intermolecular forces that make up any material. Intermolecular forces are responsible for the liquid being pulled inward. The main difference between surface energy and surface tension is that surface energy is defined as the amount of work that is done per unit area to stretch the surface while surface tension is defined as the force per unit length of the surface.

What is surface energy?

Surface energy is one of the key properties of solid and is the interfacial tension between the solid-gas interface. It is represented as γsg where s and g stand for solid and gas respectively. For a surface to have strong interactions, the solid should have high surface energy like in adhesion. When the surface has low surface energy, it becomes difficult while coating and thus the surface energy must be raised. This is done for treatment of corona which thus improves adhesion. Newton per metre is the unit of surface energy. The equation of surface energy is given as:

Surface energy = (energy)/(area)

Following is the table of surface energy for a few materials:

Material
Surface energy J.m-2
KCl
0.11
Glass
4.4
Limestone
24
Diamond
5.24
Graphite
68
Granite
200



What is surface tension?

Surface tension is the property of liquid and originates from the cohesive force between the molecules in the liquid. Surface tension is governed by intermolecular interactions. It is represented as γlg where l and g stand for liquid and gas. Newton per metre is the unit of surface tension. The equation of surface tension is given as:

γ = F/d

Where,
      γ is the surface tension
      F is the force applied to the liquid
      d is the length where the force acts

Following is the table of a few liquids with their surface tension:

Liquid
Temperature at ℃
Surface tension
Mercury
20
465.0 mN.m-1
Silver
970
800.0 mN.m-1
Gold
1070
1.0 N.m-1
Copper
1130
1.1 N.m-1
Water
100
58.9 mN.m-1
Olive oil
20
32.0 mN.m-1

Interested to learn more about other Physics related concepts like periodic motion, linear accelerator, etc, visit BYJU’S.



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