Dependence of Surface Tension on Temperature and Density in the Interface of Liquid & Vapour

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Khorsandi, Zahra | 2011

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 42699 (03)
University: Sharif University of Technology
Department: Chemistry
Advisor(s): Parsafar, GholamAbbas
Abstract:
In this thesis dependency of surface tension ( ) on temperature (T ) and density (?), for spherical and nearly spherical fluids like argon has been investigated, using an effective Lennard – Jones (12,6) potential along with a new model according to which half of surface molecules are assumed to be in the liquid phase and the other half in the vapor phase, far from the critical point. The obtained result may be expressed as ? ? ? ( The 2 2= +C D C and D parameters are independent of T and ?). Such an investigation has also been done for many fluids, but by using the extended Lennard – Jones (12, 6, 3) function as the effective pair potential, this led to the expression ? ? ?= ?C[ ]4 4 + ? + ?D E , where [ ] [ ]? ? ? ?2 2 ? and ? are density l g l g l g l gof liquid and vapor phases, respectively. ( C, D and E are independent of T and ?). The obtained expression fits well on the experimental data. Based on the used model and the assumption of the random distribution of molecules in a binary mixtures, we may expect that the ratio ? ?/ 2 versus the mole fraction is nearly third order. Such expectation is in agreement with experimental data of some liquid mixtures
Keywords:
Surface Tension ; Lennard-Jones Extended Potential (3,6,12) ; Ionic Liquids ; Lennard-jones Potential ; Liquid-Vapor Interface

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