Chromatography is a powerful tool, widely used in basic and applied research for a multitude of industries from medical diagnostics, to forensics to environmental monitoring. With the recent availability of miniature and portable gas chromatographs this tool is now more accessible to general chemistry students in a typical academic laboratory setting. This laboratory experiment utilizes chromatography to determine the unknown composition of the vapor above a known binary chemical mixture. In this experiment students prepare several binary mixtures at varied concentrations in a test tube or in a multi-neck flask equipped with a reflux condenser. The mixtures are warmed in a temperature controlled bath to maintain a constant temperature. Students then collect liquid and headspace vapor samples of each mixture and inject the samples into a mini GC. The mini GC is used to separate and quantify the binary components of both the liquid and vapor phase. Numerical Raoult’s law calculations are also performed to compare with experimental results.
Kunwar et al. (Fri,) studied this question.