drip, drip ... Here's another drop has on tap spout, bulked up and tear down.A similar pattern is familiar to anyone.Or a warm summer rain pours yearned for moisture to the ground - and again drops.And why the drop?What is the cause?Quite simply, the reason is the surface tension of water.
This is one of the properties of water, or, generally speaking, all liquids.As is known, the gas fills the entire volume, which falls, but the liquid can not do.Molecules within the volume of water, are surrounded by the molecules on all sides.But located on the surface, at the interface of liquid and gas, not being exposed on all sides but only from those molecules which are situated within the volume by gas no influence on them.
Thus on the surface of the liquid will force directed along this section perpendicular to the surface on which it acts.As a result of this force and the surface tension of water occurs.The external manifestation is the formation of similarity invisible elastic film at the interface.Due to the effects of the surface tension of a drop of water takes the form of spheres as a body having the smallest area for a given volume.
can now determine what the surface tension - is the work to change the liquid surface.On the other hand it can be defined as the energy required to break the surface of the unit.Surface tension at the border of possible liquid and gas.It is determined by the force acting between the molecules, and thus responsible for the volatility (volatility).The smaller the surface tension, the liquid is more volatile.
can determine what is the surface tension.The formula to calculate it includes a surface area and the surface tension.As mentioned earlier, the coefficient does not depend on the shape and the surface area, as determined by the strength of the intermolecular interaction, i.e.type of liquid.Different liquids, its value will be different.
surface tension of water can be changed.This is accomplished by heating, adding biologically active substances - such as soap, powder, paste.Its value depends on the purity of the water.The clearer the water, the surface tension value greater, and its significance, it is second only to mercury.
curious effect is observed when the fluid comes into contact with a solid, and gas.If we place a drop of water on the surface of the wax, it takes the form of a ball.This is due to the fact that the forces acting between the wax and the drop is less than an interaction between water molecules, with the result that the ball appears.When the force acting between the surface and the drop, will be larger than the intermolecular forces, the water will be spread evenly over the surface.This phenomenon is called wetting.
wetting effect to some extent can characterize the degree of surface cleanliness.On a clean surface of the droplet spreads evenly, and if the surface is dirty or covered with a substance that is not wetted with water, the latter going into balls.
As an example of the use of the surface tension in the industry can be reduced spherical casting parts, for example, shot for shotguns.Drops of molten metal just freeze on the fly, taking a spherical shape.
surface tension of water, like any other liquid, is one of the important parameters.It identifies some of the characteristics of liquid - such as the volatility (evaporation) and wettability.Its value depends on the parameters of intermolecular interaction.
