چكيده لاتين :
By considering the fact that the surface tension of a real fluid arises from a
combination of both repulsive and attractive forces between molecules, a new expression for the
interfacial tension has been derived from scaled particle theory (SPT) based on the work ofcavity
formation and the interaction energy between molecules. At the critical temperature, the interfacial
tension between coexisting liquid and vapour phases vanishes and the intermolecular attractive
forces must exactly counterbalance the repulsive forces associated with cavity formation. The
effective Lennard-Jones energy parameter has been calculated by using a simple equation derived
from SPT for a range ofpure fluids including noble gases, diatomic and triatomic gases, short and
medium length hydrocarbons, aromatic compounds, oxygen containing compounds. The evaluated
Lennard-Jones energy parameters and Reissיs SPT theory were used to calculate the surface tension
ofpure compounds near critical temperature and were compared with the experimental data. The
results indicated that the developed SPT in this work calculates the surface tensions much closer to
the experimental data compared with those Reissיs SPT theory .
