Surface Tension
Definition and meaning of Surface Tension in chemistry.
Surface tension is the cohesive force at the surface of a liquid that causes it to behave as a stretched elastic sheet, resisting external forces. It arises due to the unbalanced attractive intermolecular forces experienced by the molecules situated at the liquid boundary.
In more detail
In the bulk of a liquid, molecules are pulled equally in all directions by neighboring molecules. However, molecules at the surface do not have identical molecules above them, leading to a net inward pull. This creates a state of tension that naturally minimizes the surface area of the liquid, causing phenomena such as the spherical shape of liquid droplets. Surface tension is heavily influenced by the type of intermolecular forces present, with stronger forces leading to significantly higher tension.
Key facts
| Field | Physical Chemistry |
|---|---|
| Formula | H2O |
| Cause | Unbalanced cohesive intermolecular forces at the surface |
| Effect | Minimizes the overall surface area of the liquid |
The exceptionally high surface tension of liquid water (H2O) allows small insects like water striders to walk directly on the surface of a pond without sinking.
Frequently asked questions
How does temperature affect surface tension?
As temperature increases, the kinetic energy of the molecules disrupts intermolecular forces, generally causing the surface tension of the liquid to decrease.