The mixed melting point method is a standard technique many introductory organic chemistry students utilize to unambiguous identify unknown solids.  However, students are not challenged by this experiment because several unknowns commonly used are intensely colored, which allows the students to readily identify their unknown based on color.  An alternative approach is to provide the students with two unknowns which must be identified through the eutectic point.   By preparing mixtures of the unknowns in different ratios and determining the melting points, the students are able to construct a phase diagram in order to discover the eutectic point.  Using a guided inquiry approach, the students can determine the identity of their unknown samples and develop a better understanding of phase transitions.   Preliminary data and class materials will be presented along with a discussion of how the mixed melting point experiment can be improved to provide a more meaningful learning outcome.

Determining the eutectic point through mixed melting points in the second-year organic chemistry laboratory

247th National Meeting (2014)

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