 
Evaluating Volumetric and Other Thermodynamic Properties by Means of Cubic Equations of State©  
Baudilio Coto Department of Chemical and Environmental Technology ESCET, Rey Juan Carlos University C/ Tulipan Móstoles ( Madrid ) 28933 Spain mail to: baudilio.coto@urjc.es  
Immaculada Suárez Department of Chemical and Environmental Technology ESCET, Rey Juan Carlos University Móstoles ( Madrid ) 28933 Spain  
Abstract  
The use of equations of state to evaluate volumetric properties is straightforward for students, at least when the ideal gas equation of state is used. The application of a more complicated equation of state, as a cubic equation, is a little more difficult, specially for the determination of volume. In addition, the use of such equations to determine some other thermodynamic properties results extremely complex for students both from the numerical and theoretical point of view. The use of Maple to solve involved equations, to manage obtained functions and to display functional dependencies allows students both to obtain required numerical values and to understand the meaning of the calculations. This work is related with the evaluation of non idealities from several points of view. The Maple sheet allows to determine volumetric properties and compare values obtained from the ideal gas and the Soave (SRK) equations of state. Several aspects of the calculation as the effect of pressure, the lowest available volume, the number of roots, and the relation between volume and compresibility factor are analyzed. Additional thermodynamic properties are considered. Fugacity coefficient and residual enthalpy are determined from well known thermodynamic relationships and the SRK equation of state. Deviations from ideality are analyzed in terms of all the functions determined.  
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Comments to: Baudilio Coto at baudilio.coto@urjc.es  
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