scoresvideos

🔬general biology i review

key term - Surface tension

Citation:

Definition

Surface tension is the property of a liquid that causes its surface to behave like a stretched elastic membrane. This phenomenon occurs due to cohesive forces between liquid molecules at the surface, leading to a minimized surface area. Surface tension plays a crucial role in various biological processes, such as the formation of droplets, capillary action, and the ability of some organisms to walk on water.

5 Must Know Facts For Your Next Test

  1. Surface tension is measured in force per unit length, typically expressed in dynes per centimeter (dyne/cm).
  2. Water has a relatively high surface tension compared to other liquids due to strong hydrogen bonding between water molecules.
  3. Surface tension allows small objects, like a needle or a water strider insect, to float on water without sinking.
  4. Temperature affects surface tension; as temperature increases, surface tension typically decreases because increased molecular motion reduces cohesive forces.
  5. Surfactants are substances that can lower surface tension when added to a liquid, which is important in various applications like detergents and soaps.

Review Questions

  • How do cohesion and adhesion relate to the concept of surface tension?
    • Cohesion refers to the attraction between similar molecules, while adhesion is the attraction between different molecules. Surface tension arises from cohesive forces among liquid molecules at the surface, leading them to behave as if they are under tension. Adhesion plays a critical role as well; for instance, when water interacts with a solid surface, adhesive forces can pull water molecules up along that surface, which is seen in capillary action.
  • Discuss how temperature influences surface tension and provide an example of its biological significance.
    • Temperature significantly affects surface tension because an increase in temperature generally leads to a decrease in surface tension. This happens because higher temperatures increase molecular motion, reducing the cohesive forces among the molecules at the surface. An example of this biological significance is in aquatic environments; warmer water has lower surface tension, which may affect how organisms interact with the water's surface, influencing behaviors like feeding or movement.
  • Evaluate the importance of surfactants in altering surface tension and their implications in biological systems.
    • Surfactants are compounds that lower the surface tension of liquids by disrupting cohesive forces among liquid molecules. In biological systems, surfactants play essential roles; for example, pulmonary surfactant in the lungs reduces surface tension in alveoli, preventing collapse during exhalation and facilitating gas exchange. Understanding how surfactants operate not only helps explain vital physiological processes but also informs medical treatments related to respiratory conditions and other applications where managing surface tension is critical.