Resumen de Fractional Distillation and GC Analysis of Hydrocarbon Mixtures
An introductory experiment involving the fractional distillation of a three-component hydrocarbon mixture and analysis of the recovered fractions by gas chromatography is described. It has been used in a general chemistry sequence that includes a section on organic chemistry, but it is also well suited for an introductory organic chemistry laboratory course. The hydrocarbon mixtures are given to student groups as unknowns. They contain an alkane or cycloalkane, an alkene or cycloalkene, and an alkyl-substituted aromatic hydrocarbon. Five unknown mixtures are analyzed by the lab class. Supplied with the following information, the students identify the three species in their mixture: the names, structures and boiling points of all 15 hydrocarbons used to make the five unknowns; the IR and 13C NMR spectra of each of the three species in their particular unknown; and the experimentally determined boiling points. Representative GC results from student fractional distillations are included. This lab experiment is part of an effort to develop a general chemistry sequence for engineering students involving active learning and using the theme of "Chemistry and the Automobile".
