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Adhesion is the tendency of dissimilar particles or surfaces to cling to one another. (Cohesion refers to the tendency of similar or identical particles and surfaces to cling to one another.) The forces that cause adhesion and cohesion can be divided into several types.
Cohesion, along with adhesion (attraction between unlike molecules), helps explain phenomena such as meniscus, surface tension and capillary action. Mercury in a glass flask is a good example of the effects of the ratio between cohesive and adhesive forces.
The balance between the cohesion of the liquid and its adhesion to the material of the container determines the degree of wetting, the contact angle, and the shape of meniscus. When cohesion dominates (specifically, adhesion energy is less than half of cohesion energy) the wetting is low and the meniscus is convex at a vertical wall (as for ...
This occurs between water and glass. Water-based fluids like sap, honey, and milk also have a concave meniscus in glass or other wettable containers. Conversely, a convex meniscus occurs when the adhesion energy is less than half the cohesion energy. Convex menisci occur, for example, between mercury and glass in barometers [1] and thermometers.
The drop adhesion to a solid can be divided into two categories: lateral adhesion and normal adhesion. Lateral adhesion resembles friction (though tribologically lateral adhesion is a more accurate term) and refers to the force required to slide a drop on the surface, namely the force to detach the drop from its position on the surface only to ...
Cohesion (chemistry), the intermolecular attraction between like-molecules; Cohesion (computer science), a measure of how well the lines of source code within a module work together; Cohesion (geology), the part of shear strength that is independent of the normal effective stress in mass movements; Cohesion (linguistics), the linguistic ...
Adsorption is the adhesion [1] of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. [2] This process creates a film of the adsorbate on the surface of the adsorbent . This process differs from absorption , in which a fluid (the absorbate ) is dissolved by or permeates a liquid or solid (the absorbent ). [ 3 ]
In some cases, the adsorbed molecule is chemically bonded to the surface/material, providing a strong adhesion and limiting desorption. If this is the case, desorption requires a chemical reaction which cleaves the chemical bonds. One way to accomplish this is to apply a voltage to the surface, resulting in either reduction or oxidation of the ...