Cohesion and Adhesion
Molecules of a liquid are bound to each other by force known as cohesive forces which give rise to a situation where there is a tendency of the liquid to remain as one assemblage rather than behave as a gas that fills the entire space where it is confined.
Force between molecules of a fluid and molecule of a solid boundary surface is known as adhesive force. If the adhesive force between molecules of a particular liquid and a particular solid is greater than the cohesive force between the liquid molecules, the liquid tends to crowd toward the solid and the area of contact between the liquid and the solid tend to increase. This is why water wets glass but mercury will not and water will also not wet wax or greasy surface.
Cohesion means intermolecular attraction between molecules of the same liquid.
Adhesion means attraction between molecules of a liquid and the molecules of a solid bounded surface in contact with the liquid.
