Question

What is the relationship between capillary action and intermolecular forces? Show all work.

Answer 1

The flow against the forces of gravity is called capillary action. For e.g. transportation of water from the roots to leaves. Capillary action is the movement of a liquid along the surface of a solid caused by the greater attraction of the liquid's molecules to the surface of the solid than to each other.

intermolecular forces:

Forces in Capillary Action

Three main forces in a capillary action are:

• Cohesive force: intermolecular bonding of a substance where its mutual attractiveness forces them to maintain a certain shape of the liquid.
• Surface tension: forces of attraction between like molecules
• Adhesive force: forces of attraction between unlike molecules

Decreased surface tension, increases capillary action. Decreased cohesive forces also increases capillary action. Increased adhesive forces increases capillary action.

The intermolecular forces within the liquid exceed those between the solid and the liquid, so a convex meniscus forms and capillary action works in reverse.

The height h of a liquid column is:

where is the surface tension (force/unit length), θ is the contact angle, ρ is the density of liquid (mass/volume), g is local acceleration (length/square of time), and r is radius.