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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