Final answer:
Surface tension arises due to cohesive forces that pull surface molecules of a liquid inward, creating an effect where the surface acts as an elastic membrane. Stronger intermolecular forces lead to greater surface tension. Surface tension is the result of energy required to overcome these forces and expand the surface area.
Step-by-step explanation:
Surface tension is a phenomenon that results from cohesive forces between molecules at the surface of a liquid. Molecules on the surface experience a net inward force because they lack neighboring molecules above them and are only pulled sideways and downwards. This net inward force tends to reduce the surface area, which leads to surface tension acting tangentially, as if the surface is an elastic membrane.
Intermolecular forces play a crucial role in this effect. These forces result in the liquid's surface contracting to the smallest possible area. For the surface molecules, the stronger these intermolecular forces, the more pronounced the net attractive force toward the center, and hence, the greater the surface tension. This is why a substance like water, with strong hydrogen bonds, has higher surface tension compared to many other liquids.
The elasticity of the surface, which allows it to resist external force, is due to the energy/work required to increase surface area. This is because forming new surface requires breaking intermolecular bonds, which demands energy due to the strong cohesive forces. Therefore, minimizing surface area results in a state of lower potential energy, making the surface act like an elastic layer.