12.tension, surface, makes a,, aquires a spherical shape, because for a given volume, a sphere has minimum, surface area.,, drop spherical.,, Surface Energy: To increase the surface area, some work has, to be done, against the inward pull. It is for this reason that the drop of a liquid,, Inward pull of, Fig. Thus the unit of, surface tension (y) is dyne per cm or newton, per meter in S.I., a,, system.,, Further, as a result of the downward/inward pull on the molecules at the,, surface, the surface of a liquid tends to contract to the smallest, possible area for,, a,, given volume of the liquid (Fig. Forces acting,, on a,, the bulk of the,, and at the,, liquid,, molecule in,, liquid.,, liquid,, is defined as the force acting at, right, angles to the surface along one cm length of the surface. Hence, this property of liquids is called surface tension., The surface tension of,, downward force),, Bulk molecule,, Fig. As a result of the, downward/inward pull on all molecules lying at the surface of a, liquid, the surface behaves as if it were under tension like a stretched, membrane. The unbalanced attractive forces acting downward tend to, draw the surface molecules into the body of the liquid and, therefore, tend to reduce the surface to a minimum. The,, downward atractive forces are greater than the upward forces because, there are more molecules of the liquid below than in air above the, surface. Again consider a molecule B at the surface of the liquid. 11, and therefore, cancel the effect of one,, Surface molecule,, (experienoces, resuitant,, another. This,, is attracted equally in al directions by other molecules which, surround it as shown in Fig. It is a characteristic property of liquids which arises due to the,, fact that molecules ofa liquid at the surface are in a different situation from those in the interior of the liguid, Consider a molecule A somwhere in the body of the liquid. SURFACE TENSION,, Definition: The existence of strong intermolecular forces of attraction in liquids gives rise to an, important property known as surface tension. The liquids possess,, liquids differ,, ofthe,, properties of liquids,, common,, of,, properties,, are:,, (5) Refractive Index, Vapour Pressure, (4) Optical Activity, (1) Surface Tension, (2) Viscosity, (3), (6) Dipole moment etc., the chemical constitution of each liquid., These properties of liquids help us in determining, 3.5. As it is clear, the,, law,, general, liquid.,, each,, as,, done,, Some,, by,, like gases, the liquids do not obey anv, which are characteristic,, from gases in many aspects.
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