Raman spectroscopy can be used to identify vibrational and rotational modes of molecules, which constitute their structural fingerprint and hence, can be used for quantification. Two laboratory experiments were designed/improved by using Raman spectroscopy to quantify ethanol in samples. The first laboratory activity was created for quantitative analysis. This lab requires students to measure the percent ethanol concentration in a range of commercial alcoholic beverages using a standard curve they develop from ethanol standards. Students will compare these results to those measured in a related lab using infrared spectroscopy (IR) as well as to the reported ethanol concentration in the commercial beverages. Through this laboratory activity, students obtain knowledge of the similarities and differences between Raman and IR spectroscopy. The second experiment looked to improve a preexisting organic chemistry lab where students perform simple and fractional distillations on fermented molasses. Research was undertaken to determine which combination of yeast strain and which brand of blackstrap molasses would produce the most ethanol. Ethanol concentrations were traditionally measured using density but now students will also use Raman spectroscopy and then compare the results from both methods.

Determination of ethanol concentration using Raman spectroscopy

255th National Meeting (2018)

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