I have that a book that says "Low surface tension of a liquid helps it to spread over a larger area." . My question is How and Why ? When I say that a liquid A has a lower surface tension than liquid B , does that mean that the cohesive forces and the force with which molecules of liquid A pulls other molecules towards themselves for A are less than that of B ?
There are two types of intermolecular forces:
1) Cohesive forces: Intermolecular forces (such as those from hydrogen bonding and Van der Waals forces) which cause a tendency in liquids to resist separation. These attractive forces exist between molecules of the same substance
2) Adhesive Forces: Attractive forces between unlike molecules. They are caused by forces acting between two substances, such as mechanical forces (sticking together) and electrostatic forces (attraction due to opposing charges)
A liquid with low cohesive attraction and more adhesive attraction has a low surface tension. It sticks more to the container or surface than to itself(like benzene) and spreads itself as much as possible. Whereas mercury has high surface tension and forms balls when left on a smooth surface, in effect reducing its surface area.