Getting Physical

Our first lab of the semester in “Introduction to Organic Chemistry” was a “physical properties” exploration activity. I incorporated some of the features that I like to include in experiments into this lab. The students were assigned either vanillin or camphor as their solid and limonene or ethyl lactate as their liquid. The four possible combinations of liquid and solid avoided having all the students do exactly the same experiment. The students determined the melting temperature range of their solid with a melting point apparatus. They observed the solubility of their solid in water and in hexane.

They measured the density of their liquid by weighing 10 ml of their liquid. They determined the boiling temperature range of their liquid by boiling the liquid in a test tube. Finally, they observed the miscibility of their liquid in water and in finally. The experiment offered the students an opportunity to get acquainted with the lab space as well as perform some familiar techniques such as weighing, measuring out volumes in a graduated cylinder, reading a thermometer, and heating things on a hot plate. Melting point determination was a new technique for them.

The students entered their results on a spreadsheet before leaving the lab. The class data was posted on the course website and used in their lab report. Posting class data helps students compare their results to their peers’ data. It also gives them an opportunity to perform data analysis calculations. The lab report involved explaining the phenomena they had observed in terms of non-covalent interactions such as hydrogen bonding.

Student handout available at OChemOnline Wiki.

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