Difference between Adhesion and Cohesion -->

Difference between Adhesion and Cohesion


Adhesion and cohesion are associated with macroscopic properties of the material. Both of them are kind of attractive force, which govern the shape of liquids over a surface.

Adhesion Adhesion - Adhesion is the attraction between unlike molecules.
Cohesion - Cohesion is the attraction between molecules of the same material.

Cohesive force is responsible for surface tension. Both adhesive and cohesive force are responsible for the capillary action of liquids.

The shape of the meniscus of liquid in a tube depends upon these forces. If cohesion is greater than the adhesion force between liquid and tube material, then the shape of the meniscus will be convex (Obtuse angle of contact). If adhesive force greater than cohesion then the meniscus will be concave. If these forces are equal, the surface is horizontal (Acute angle of contact).

Consider some liquid is poured on a surface. If adhesive force stronger, it pulled down the liquid and cause wet. If cohesive force is stronger, liquid molecule attracts each other, trying to retain the spherical shape.

- What is meant by Viscosity 
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