Question

How are cohesion and adhesion related to surface tension?

Answer 1

Hint: The tendency of the liquid or fluid surfaces to shrink into a minimum surface area and resist the external forces is called the Surface tension of that liquid.

Complete answer:
The collective intermolecular forces that exist between the like molecules of a substance are called the Cohesive forces, and these forces between the liquid molecules are responsible for the phenomenon of surface tension. Surface tension is the property of the surface of the liquid. The tendency of the liquid molecules to resist the external forces due to the presence of cohesive forces amongst them- and achieve the state of the minimum surface area is called surface tension. It arises due to an imbalance of the intermolecular forces from all directions- in a bulk medium. The attraction between the water molecules at the liquid surface is not balanced, and a net force is present in a particular direction.
The property of attraction between the molecules of the same kind is called cohesion, and the forces present between them are called the cohesive forces. Whereas, the property of attraction between the molecules of two different kinds is called adhesion, and the forces present between them are called adhesive forces.

The cohesive forces present between the water molecules keeps them together and provides stability to them. The hydrogen bonding between the water molecules accounts for their stability and helps them to resist the external forces. The adhesive forces help the water molecules to stick to other surfaces like glasses, leaves, or any other plant surfaces. The water molecules stick to these surfaces and thus do not runoff.

These two forces together aid in the process of surface tension by maintaining a balance between the water molecules and outside surfaces and the environment. The water molecules experience a net force in a particular direction and thus attain the minimum surface area shape or become water droplets.

Note: The property of cohesion and adhesion provides surface tension to the water and this is responsible for a various phenomenon like- movement of spiders and various insects on the water surfaces, transportation of water in the plants, dispersal of seeds in plants, etc.