STUDY OF KINETIC CHARACTERISTICS OF VARIOUS LIQUIDS

The thermal motion of molecules and the forces of intermolecular interaction are the fundamental causes that determine the frequency of vibrations in liquids. In contrast to the crystal structure of solids, where atoms or molecules are fixed in lattice sites and vibrate around these positions, in liquids, particles vibrate near volatile centers of equilibrium. These fluctuations are accompanied by periodic "jumps" of molecules to new, also temporary, positions, which characterizes the dynamic nature of the liquid state. The link between the microscopic movement of molecules and macroscopic viscosity is the sedentary lifetime, the time during which a molecule oscillates around one equilibrium position before making a "leap." The longer the molecule oscillates near the equilibrium point, the rarer the displacement acts occur and the higher the viscosity. The concept describing the theory under consideration was developed by J.I. Frenkel. On the other hand, A.E. Bachinsky found that the viscosity of liquids is related to the "free" volume, which already depends on temperature. The oscillation frequency, sedentary life time, activation energy, and free volume of various liquids have been studied. To determine the free volume, data on vapor densities and enthalpies at various temperatures were used, which were calculated using linear extrapolation and the Watson formula. Using the viscosity theories of G. Eyring and J.I. Frenkel, the values of oscillation frequencies and sedentary life time for more than twenty different liquids were obtained. The calculations showed that near the boiling point, the proportion of free volume increases to 7 ‒ 9 % (excluding formic acid). A.E. Bachinsky found that with a fixed volume, the viscosity of a liquid remains almost unchanged, despite variations in pressure and temperature. 

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