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How Does Cohesion Relate to Surface Tension?

Water possess some qualities that allow you to use it to wash items, float on it, get irritated by a faucet drip and observe insects walking on it. The diverse properties related to how water molecules hold onto other molecules, other substances in the water, the temperature and the property of things interacting with the water. The strength of molecules holding onto each other provides the basic property for surface tension.

Bonding
- A group of atoms that stick or bond together make up a molecule. Many types of molecules exist. Molecules may bond with other molecules. Hydrogen bonding forms to make an important type of molecule in surface tension. Water molecules include two hydrogen atoms and one oxygen atom. The hydrogen atoms in water stick, or bond, to the oxygen atoms. Oxygen and hydrogen bonding occurs by sharing electrons, according to the University of Arizona Department of Biochemistry and Molecular Biophysics Departmen. Hydrogen bonds, classified as weak bonds, break apart easily but rejoin quickly.
Cohesion
- Cohesion relates to the attraction of one molecule to another molecule. Hydrogen molecules attract other hydrogen molecules. Observing beads of water or dewdrops on the morning grass or a drop of water on a surface or sliding down the window demonstrates the attraction of the molecules as they stick to form the beads instead of flattening out.
Tension
- Cohesion works to hold liquid molecules together. On the surface of a liquid, the molecules exert more cohesion or attraction to the water molecules around and under them than to the molecules, such as air, above the surface. This stronger cohesion on the surface, or surface tension, results in a stronger bond than in the underlying water molecules. Therefore, surface tension results from a special property of cohesion when the molecule bonds stronger with similar molecules, rather than forming with molecules above the surface, according to HyperPhysics.
Variables
- The cohesion of molecules may change depending on certain conditions or types of connecting molecules. Heating water decreases the surface tension. Warm water provides more efficient cleaning and rinsing than cold water because it bonds better with the washed item. Some types of detergents also decrease surface tension. Placing an item to float on water, then adding detergent until the item sinks helps demonstrate the decreasing surface tension. Agitating the water causes changes in surface tension while the bonds break and reform. Washing machines agitate the water and move the clothing to help break surface tension and allow the water to mix more thoroughly with the fibers.

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