In this study, a new technique for obtaining binary liquid-vapor phase diagrams for Physical Chemistry Laboratory is proposed. An apparatus similar to that of J. McCormick from the University of Kansas was devised to collect both liquid and vapor fractions at several different compositions. This technique, however, differs in that there is no reliance upon refractometry to determine the composition of the liquid and vapor phases. Rather, Vernier's tabletop Gas Chromatograph is utilized to quickly resolve the composition of the phases. Boiling points and peak integrations and retention times are recorded by the student and a binary liquid-phase diagram can easily be constructed in Excel.  Results are encouraging for ideal systems (for example, cyclohexane and toluene) and further investigation is ongoing for non-ideal systems which display azeotropes (for example, diethyl ether and cyclohexane).  This experiment is now in the rotation of physical chemistry laboratories at Henderson State, as it gives students experience working with modern instrumentation while doing a classic investigation.<br/>

Binary liquid-vapor phase diagrams with desktop gas chromatography

253rd National Meeting (2017)

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