Dynes per Centimeter

Definition

Dynes per centimeter is the unit used to measure surface tension, which is the force per unit length acting on the surface of a liquid. It quantifies the cohesive forces between the molecules at the liquid's surface, which give rise to phenomena like surface tension and capillary action.

5 Must Know Facts For Your Next Test

1. Dynes per centimeter (dyne/cm) is the standard unit for measuring surface tension, with typical values ranging from 20-80 dyne/cm for common liquids.
2. Surface tension is responsible for the curved, meniscus shape of the surface of liquids in containers, as well as the ability of some objects to float on the surface.
3. Capillary action, driven by surface tension, allows liquids to be drawn upwards through narrow spaces, like the xylem of plants or the porous material of a paper towel.
4. Liquids with higher surface tension, measured in dynes per centimeter, generally have stronger intermolecular cohesive forces and exhibit more pronounced surface effects.
5. The surface tension of a liquid can be reduced by adding surfactants or detergents, which disrupt the cohesive forces between the molecules at the surface.

Review Questions

• Explain how the unit of dynes per centimeter is used to quantify the surface tension of a liquid.
  • The unit of dynes per centimeter (dyne/cm) measures the force per unit length acting on the surface of a liquid. This quantifies the cohesive forces between the molecules at the liquid's surface, which give rise to the phenomenon of surface tension. Liquids with higher surface tension, measured in higher values of dyne/cm, exhibit stronger intermolecular cohesive forces and more pronounced surface effects, such as the ability to support the weight of objects on the surface or to draw liquids upwards through narrow spaces via capillary action.
• Describe the relationship between surface tension, measured in dynes per centimeter, and the cohesion and adhesion of liquids.
  • The surface tension of a liquid, measured in dynes per centimeter, is directly related to the cohesive forces between the molecules at the liquid's surface. Liquids with higher surface tension have stronger intermolecular cohesive forces, which allow the surface to behave like an invisible 'skin' and enable phenomena like capillary action and the ability of some objects to float on the surface. Conversely, the addition of surfactants or detergents, which disrupt these cohesive forces, can reduce the surface tension of a liquid, measured in lower values of dyne/cm. The balance between cohesion (within the liquid) and adhesion (to other surfaces) is what determines the surface tension and associated behaviors of the liquid.
• Analyze how the surface tension of a liquid, quantified in dynes per centimeter, influences the capillary action and wetting properties of that liquid.
  • The surface tension of a liquid, measured in dynes per centimeter, is a crucial factor in determining its capillary action and wetting properties. Liquids with higher surface tension, indicated by higher dyne/cm values, exhibit stronger intermolecular cohesive forces at the surface. This allows the liquid to be drawn upwards through narrow spaces via capillary action, as the cohesive forces overcome the downward pull of gravity. Additionally, liquids with higher surface tension tend to have a greater contact angle with solid surfaces, meaning they do not 'wet' those surfaces as readily. Conversely, liquids with lower surface tension, measured in lower dyne/cm values, are more likely to spread and wet surfaces due to the weaker cohesive forces at the surface. Understanding the relationship between surface tension and these physical properties is essential for predicting and controlling the behavior of liquids in various applications, such as the design of microfluidic devices or the formulation of cleaning products.

Related terms

Surface Tension:

The cohesive force between liquid molecules at the surface, which creates an invisible 'skin' and allows some objects to float or insects to walk on water.

Capillary Action:

The ability of a liquid to flow through narrow spaces without the assistance of, and in opposition to, external forces like gravity.

Cohesion:

The intermolecular attractive forces between like molecules within a substance, which give liquids and solids their distinct properties.