[Chemistry Class Notes] on Difference Between Adhesion and Cohesion Pdf for Exam

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:

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.