The Origin of Surface Tension

The Origin of Surface Tension

S. Majid Hassanizadeh

How is surface tension related to molecular properties and the molecular description of materials? The explanations provided in much of the literature are wrong and/or incomplete. Often, surface tension is linked to the forces of cohesion between molecules of a liquid, which is only one of the intermolecular forces in a fluid – a force which is commonly almost negligible within a fluid – but becomes significantly larger in the interfacial region between two fluids. A much stronger intermolecular force is the impulse due to the molecules hitting each other. In this article, we explain the interplay of these forces and show that while they result in a compressive and isotropic state of stress within fluids under equilibrium conditions, their resultant is anisotropic in the interfacial region and results in a less compressive or even tensile force in the tangential direction. It is this pressure deficit that is experienced as surface tension.

InterPore Journal 1(1) (2024)
Corresponding Author: S. Majid Hassanizadeh

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