Difference Between Adhesion and Cohesion

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What is Cohesion and Adhesion?

Many aspects explain various things on adhesion and cohesion, meaning and examples, which we observe in our daily life. Although, at times, we miss to focus on these little things, and these help us to keep our lives going on earth. The adhesion and cohesion forces are one of both phenomena. Although they sound to be similar, they are completely known to occur in different terms.

Surface tension is one of the important physical properties of water that describes the relationship between adhesion and cohesion.

Coming to the definitions, the tendency of either two or more different molecules to bond with each other is called Adhesion. In contrast, the attraction force between the same molecules is referred to as Cohesion.


About Adhesion and Cohesion

Adhesion forces can be one of the electrostatic forces' results exerted on various substances. Simultaneously, the cohesive forces are associated with the Van der Waals forces and hydrogen bonding that cause liquids like water to withstand the separation. 

When a glass surface is poured with water, the forces of both adhesive, cohesive act on the water's surface. Also, a strong adhesive force tends the liquid to spread over the surface; on the other side, a strong, cohesive force is responsible for forming water droplets on the water surface.

Both the adhesion and cohesion forces vary in their strengths. For example, if the cohesion forces between water molecules are stronger compared to the adhesion forces between them, then the individual molecules present in them will attract towards each other hence resulting in settling. If the adhesion forces of the water surfaces are stronger than the water molecules' cohesion forces, the water tends to disperse then.


Difference Between Cohesion and Adhesion

Let us discuss the adhesion and cohesion difference.

Adhesion and cohesion are attraction forces, exist between different and the same molecules, respectively. Though they sound to be similar, they differ from each other. Let us come to know how cohesion differs from adhesion, and the primary differences between them are tabulated below:

Adhesion

Cohesion

Adhesion takes place between the two dissimilar molecules or substances.

When any two similar molecules or substances face the force of attraction, the resultant force is called a cohesion force.

In general, adhesion is the force of attraction, which is present between the water molecules and the walls of xylem vessels.

Cohesion force is rampant among the water molecules.

Meniscus and capillary action and (the curved surface, formed by any liquid, that exists in a cylinder) are the adhesion effects.

The meniscus, capillary action, and surface tension are the effects of cohesion.

Adhesion caused by the mechanical or electrostatic forces that exist among two classes of different substances.

Cohesion is caused by Van der Waals forces and hydrogen bonding.

Any of the strong adhesion forces can cause the liquid to spread all over the surface.

A strong cohesion force forms water droplets on any surface.

Various molecules tend to attract one another.

Similar molecules tend to stick together.


Relationship and The Meaning of Cohesion and Adhesion

In general, cohesion and adhesion forces exist together; you can find these respective forces in various activities and processes. Consider the example, meniscus, which is a

liquid surface curvature stored in a tube or container, is caused by both adhesion and cohesion. The attraction force between the edges of liquid and the container wall is called adhesion. The attraction force between the water molecules, which makes the liquid surface curved in the middle, is given cohesion.

Also, the meniscus shape is decided by these forces. If the cohesion force, which exists between the liquid molecules, is more than that of adhesion force existing between the liquid and the tube's inner surface, the meniscus shape will be convex. For example, mercury, filled in a glass tube. Similarly, if adhesion is more than that of cohesion, the meniscus will be concave. For example, water, filled in a glass tube. The surface will be horizontal if the cohesion is equal to adhesion.

Let us suppose you spill some water on a surface. If the adhesive force is strong, then the water will get absorbed soon by the surface, and also it will go wet. Whereas, if the cohesive force is strong, there will be more attraction between the water molecules than between the surface and water molecules. So, the surface absorbs less water.


Differences Cohesion vs. Adhesion

Based on the given information above, a few key differences between cohesion vs adhesion are listed. 

Cohesion

Adhesion

Cohesion is an intermolecular attraction type.

It is an intramolecular attraction type.

It includes Van Der Waals forces and hydrogen bonding.

It includes mechanical or electrostatic attractions.

It causes the formation of capillary action, water droplets, and surface tension of a liquid.

A liquid spreads on a solid surface because of the adhesion, such as paints, Glue, and cement work.

FAQ (Frequently Asked Questions)

1. Mention any application of Adhesive and Cohesive Forces in daily life?

Ans. There is much difference between cohesive and adhesive force. When a fly walks on a vertical glass piece, the adhesive forces between the glass and its tarsal pads become sufficient to resist both the tendency to slide downward and the tendency to fall away from the glass surface.

The behavior of water molecules is a known example of cohesion. Every water molecule can result in the formation of four hydrogen bonds with their neighbor molecules. The strong attraction present between the molecules makes them "sticky" or draws them together.

Because the water molecules are more strongly attracted to each other to that of other molecules, they form droplets on the surfaces. For example, dew drops, form a dome when filling a container before it is spilling over the sides. The surface tension formed by cohesion allows it for the light objects to float on water with no sinking. For example, such as water striders walking on water.

2. How do the Adhesion and Cohesion processes work in plants?

Ans. The process works similarly in plants as anywhere else. Through xylem, both are important processes in the cohesion-tension theory of water movement. Xylem cells fall when working, and water molecules adhere to their cell walls. In these narrow tubes, adhesion leads to a capillary movement of the water. Also, up the xylem, there is a certain amount of root pressure forcing the water. However, the water does not climb far in the tubes. The cohesion force among the water molecules makes the tube of water a complete stand essentially from the leaves to the roots.