What is the Difference Between Adhesive and Cohesive Forces?

The main difference between adhesive and cohesive forces lies in the types of molecules they act between:

• Adhesive forces are attractive forces between molecules of different types (dissimilar molecules or substances). These forces can be mechanical forces or electrostatic forces. Adhesive forces cause dissimilar surfaces to stick together and can result in the formation of a thin, relatively uniform film over the surface, a process known as wetting.
• Cohesive forces are attractive forces between molecules of the same type (similar molecules or substances). These forces are associated with hydrogen bonding and van der Waals forces. Cohesive forces cause the formation of clusters of similar molecules and are responsible for the bulk property of liquids resisting separation, such as the formation of water droplets.

In summary, adhesive forces act between dissimilar molecules or surfaces, while cohesive forces act between similar molecules or surfaces. These forces play a crucial role in determining the properties and behavior of liquids, such as surface tension, wetting, and the shape of droplets on a surface.

Comparative Table: Adhesive vs Cohesive Forces

Adhesive and cohesive forces are both intermolecular forces that act on liquids, but they differ in the types of molecules they act upon and their effects. Here is a table summarizing the differences between adhesive and cohesive forces:

In summary, adhesive forces cause different molecules or surfaces to cling to each other, while cohesive forces cause like molecules to stick to each other due to mutual attraction. Both forces play a crucial role in determining the properties and behavior of liquids.