Surface Chemistry, Surface Tension and Capillary Action Surface Tension: → Surface tension is a characteristic of surface of liquids due to which it try to decrease its area. For this purpose, a force of attraction is applied betweem the molecules of liquids on the surface. For this reason, surface of a liquid behave like a stretched membrane. → Consider a molecule P some where in the body of the liquid. This is attracted equally in all dieactions by auther molecules which surround it as shown in fig and therefore cancel the effect of one another. → Consider, next, a olecule R at the surface of the liquid. THe downward attractive force are greater than the upwardr forces because there are more molecules of liquid below than that in air above the surface. These inbalanced atttractive forces acting downward tend to draw the surface mlecules into the body of the liquild and therefore, tend to reduce the surface to a minimum. → It is well know that force of attr...