Surface tension capillary action

In a liquid, intermolecular forces are strong enough to confine the molecules to a specific volume, but they are not strong enough to keep molecules from moving from place to place within the liquid. The relative freedom of motion of liquid molecules leads to three liquid properties arising from intermolecular forces surface tension, capillary action, and viscosity. ... 

I See the Saunders Interactive General Chemistry CD-ROM, Screen 13.11, Properties of Liquids (4) Surface Tension/Capillary Action/ Viscosity. 

Liquids exhibit properties such as surface tension, capillary action, and viscosity that depend on the forces among the components... 

Key Terms Surface tension Capillary action Meniscus... 

Capillary rise, or capillary action, is a second effect caused by surface tension. Capillary rise is the tendency of a fluid to rise into a narrow-diameter tube. Figure 7.22 shows this phenomenon. The tube on the far right has the narrowest diameter, so the amount of rise depends on the diameter of the tube. 

Capillary action or absorption depends on the takeup of the consolidant through the gross cell structure and voids as a result of surface-tension forces. Absorption is a factor of time, surface tension, capillary dimension and exposure, and viscosity. 

Fiber capillary action Apart from improved adsorption of biological fluids thanks to fiber high surface ratio, capillary action of fibers also contributes to cells adhesion onto the fibrous implantable medical device. Capillarity is the action by which pores in a solid transport liquid on contact, so that tissue fluids transfer from the wet end to the dry end. The kinetics of the fluid transport are governed by the surface tension... 

This equation describes the additional amount of gas adsorbed into the pores due to capillary action. In this case, V is the molar volume of the gas, y its surface tension, R the gas constant, T absolute temperature and r the Kelvin radius. The distribution in the sizes of micropores may be detenninated using the Horvath-Kawazoe method [19]. If the sample has both micropores and mesopores, then the J-plot calculation may be used [20]. The J-plot is obtained by plotting the volume adsorbed against the statistical thickness of adsorbate. This thickness is derived from the surface area of a non-porous sample, and the volume of the liquified gas. 

There are three types of Hquid content in a packed bed (/) in a submerged bed, there is Hquid filling the larger channels, pores, and interstitial spaces (2) in a drained bed, there is Hquid held by capillary action and surface tension at points of particle contact, or near-contact, as weU as a zone saturated with Hquid corresponding to a capillary height in the bed at the Hquid discharge face of the cake and (3) essentially undrainable Hquid exists within the body of each particle or in fine, deep pores without free access to the surface except perhaps by diffusion or compaction. 

Surface tension is the property of a fluid that produces capillary action, the rise and fall in a tube. 

The greater the viscosity of a liquid, the more slowly it flows. Viscosity usually decreases with increasing temperature. Surface tension arises from the imbalance of intermolecular forces at the surface of a liquid. Capillary action arises from the imbalance of adhesive and cohesive forces. 

Types of intermolecular forces Properties of liquids Surface tension Viscosity Capillary action Structures of solids Phase changes and diagrams... 

At the microscopic level, the liquid particles are in constant motion. The particles may exhibit short-range areas of order, but these usually do not last very long. Clumps of particles may form and then break apart. At the macroscopic level, a liquid has a specific volume but no fixed shape. Three additional macroscopic properties deserve discussion surface tension, viscosity, and capillary action. 

Liquids possess certain properties due to the intermolecular forces between the liquid particles. These properties include surface tension, viscosity, and capillary action. Solids may be either amorphous or crystalline in nature. 

A combination of adhesion and surface tension gives rise (pardon the pun) to capillary action. By its adhesion to the solid surface of the soil particles, the water wants to cover as much solid surface as possible. However, by the effect of surface tension, the water molecules adhering to the solid surface are connected with a surface him in which the stresses cannot exceed the surface tension. As water is attracted to the soil particles by adhesion, it will rise upward until attractive forces balance the pull of gravity (Figure 3.28). Smaller-diameter tubes force the air-water surface into a smaller radius, with a lower solid-surface-to-volume ratio, which results in a greater capillary force. Typical heights of capillary rise for several soil types are presented in Table 3.9. The practical relationship between normal subsurface water and capillary rise is presented in the following equation. 

Water flow through unsaturated soil is controlled by the same forces as capillary action and water retention (i.e., adhesion, gravity, and surface tension). Flow can occur only when the water phase is continuous from pore to pore. If gravity is the controlling force, downward flow will occur according to Darcy s law in direct proportion to the percentage of water-filled, connected pores. For example, if only half the pores in a cross section are water filled, the flow through that section will be half of that predicted by Q- K1A. 

The term capillary action describes the upward movement of a fluid as a result of surface tension through pore spaces. The fluid can rise until the lifting forces are balanced by gravitational pull (see Figure 3.28). The rise of fluid in a small tube above the water table surface, as previously discussed in Chapter 3, can be described using Equation 3.13. Lifting of fluids above the water table is a true negative pressure compared with atmospheric pressure (also described as soil suction). In soil situa-... 

Liquids possess surface tension (liquids behaving as if they had a thin skin on their surface, due to unequal attraction of molecules at the surface of the liquid), viscosity (resistance to flow), and capillary action (flow up a small tube). 

In this approach, NAs are directly deposited onto a glass support using a robot able to deliver with high precision a sample to a specific x y programmed location. The NA sample is loaded into a spotting pin (highly miniaturized stainless-steel fountain-pen nibs with a gap) by capillary action, and small volumes are transferred to a solid surface, such as a microscope slide, by direct physical contact between the pin and the solid substrate. Spot size depends on the acceleration of the pen towards and away from the slide, and the surface tension of the slide. After the first spotting cycle, the pin is washed and a second sample is then transferred to an adjacent address. A robotic control system and multiplexed print heads allow the automated immobilization of many different probes simultaneously onto the slide [29]. 

The principle of measurement is based on the fact that mercury does not wet most substances and thus, it will not penetrate pores by capillary action. Surface tension opposes the entrance of any liquid into pores, provided that the hquid exhibits a contact angle greater than 90° [115,116]. Therefore, external pressure is required to force the liquid (mercury in this case) into the pores of the material. The pressure that has to be applied to force a liquid into a given pore size is given by the Washburn equation. 

Maxima may be removed by the addition of small amounts of certain surface-active substances, e.g. Triton-X-100 and gelatin (see Sect. 3.3.3), whose action is ascribed to their effect on the mercury surface tension. When addition of such substances is not possible, the placement of a shroud around the capillary tip has been suggested to minimise convection effects [65]. An alternative is to arrange for short drop times by mechanical means. 

Capillary action, the rise of liquids up narrow tubes, occurs when there are favorable attractions between the molecules of the liquid and the tube s inner surface. These are forces of adhesion, forces that bind a substance to a surface, as distinct from the forces of cohesion, the forces that bind the molecules of a substance together to form a bulk material. By finding a relation between the height to which a liquid climbs in a tube of known diameter, we can use the height to determine the surface tension. 

The powder is moistened and compacted simultaneously under the action of capillary forces. The smaller the surface tension, the more compact is the agglomerate. 

A condition of negative capillary action is achieved. The pressure required to force water through the fabric depends on the surface tension and inversely on the fibre spacing, so that a moderately tight weave is desirable. The passage of air through the fabric is not hindered. 

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