Understanding Surface Tension

Surface tension is a physical phenomenon occurring at the boundary of a liquid, where the surface acts like a stretched elastic membrane due to molecular cohesion.

Water has high surface tension because of hydrogen bonding. This allows insects like water striders to walk on water without sinking, a remarkable example of surface tension in nature.

Factors like temperature, impurities, and surfactants can alter surface tension. For instance, detergent reduces water's surface tension, which helps it clean more effectively.

The Du Noüy ring method is a classic technique to measure surface tension. A thin wire ring is pulled from a liquid, and the force required is used to calculate the surface tension.

In medicine, surface tension is critical for lung function. Pulmonary surfactants reduce the surface tension of the fluid lining the alveoli, preventing lung collapse during exhalation.

Liquid metals exhibit high surface tension, significantly affecting industrial processes like welding. Mercury's surface tension is so strong it forms almost spherical droplets when spilled.

Geckos exploit surface tension to adhere to surfaces. Their toe pads contain tiny hairs that increase contact area, maximizing van der Waals forces for their remarkable stickiness.