Comparison of selected equations of state in evaluating the compression factors and fugacities of thirteen substances

Date

4-2007

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Ernesto J. Del Rosario

Abstract

Four two-parameter equations of state, which all have repulsive modifications of the van der Wards equation, were compared through their ability to accurately represent the empirical compressibility factors and fugacity coefficients of thirteen substances (air, argon, carbon dioxide, carbon monoxide, ethylene, hydrogen, krypton, methane, neon, nitrogen, oxygen, water and xenon). The four equations of state studied are Carnahan-Starling, Guggenheim, Reiss and Scott equations. The maximum deviations and deviation volumes were determined for each pair of equations of state and substance at the four quadrants (high pressure-high temperature, low pressure-low temperature, high pressure-low temperature, and low pressure-high temperature). All derivations of the required parameters such as the critical constants and compressibility factors, and plotting were done through Mathematica 5 I Results showed that there was no specific equation that could accurately predict the compressibility factors of all thirteen gases at all the specified conditions. The Reiss equation, however, was the best equation of state among the four and was most accurate in predicting the compression factors of the substances with the lowest deviations and deviation volumes. Fugacity coefficients, on the other hand, were evaluated through visual comparison of the plots due to the unavailability of empirical values. All four equations generally followed the trends given by the empirical plots The four two-parameter equations of state were also compared with the 13erthelot, Redlich-Kwong, van der Wards and modified Dieterici equations, all studied by Mangaldan (2005). The four two-parameter equations performed better than those studied by Mangaldan (2005). The analysis was extended by classifying the substances based on their structure namely: (I) spherical/monoatomic, (2) ellipsoidal/diatomic, (3) non-polar and (4) polar. The performance of the equations vaned for each gas type. Modification was done for the Reiss equation by replacing the attractive term with that of the Berthelot equation. The Reiss-Berthelot equation performed best at high pressure-low temperature region, especially for non-polar substances. The deviations and deviation volumes of the four two-parameter equations of state including the Reiss-Berthelot equation were compared with the EOSs studied by Biado (2007) and Dayaon (2007). The group was able to develop accurate modifications through Reiss-Berthelot, Guggenheim-Berthelot 12 and Reiss-Berthelot 1/2 equations.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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