Summer Research Program for Science Teachers
Martin J. Olivieri
How Do I Get a Pure Sample of the Molecules I Make?
1. Phrases describing compound purification techniques.
2. NMR identification of products.
I. Students research TLC, column, NMR proceedures on software or internet.
A. Succinct phrase or two explaining the principle of each method. [9-12 Content Standard E- Understandings about science and technology]
II. Have the students look up a paper about some organic research to find a compound to produce. They can also look up a reaction in a lab procedure book as in, Chemical Demonstrations, Lee Summerlin. [9-12 Content Standard A- Identify questions that guide inquiry]
A. Students will follow the steps of the procedure including the set up of the equipment put out by lab specialist.
III. At the end of the reaction show the students how to do a TLC.
A. Explain how molecules of different sizes move up the TLC paper at different rates because they get caught in the pores of the paper. [9-12 Content Standard B- Motions and forces] The larger the molecule the slower it climbs. 30-50% ethyl acetate: petroleum ether solution to make the solution rise through the TLC. Higher the percentage of ethyl acetate the greater the separation.
1.Count the number of substances present.
IV. Show students how to set up a column according to usual procedures.
A. Explain how the gel pores slow down the smaller molecules and allow the larger ones to pass through quickly.
B. Teach procedures for conducting the column.
V. Students collect the selections giving single dots on the column TLCs.
A. Solvents removed from collected samples.
B. NMR conducted on samples to see which of the samples matches the paper or approximates the expected structure. [9-12 Content Standard A- Formulate/revise explanations using evidence]
Was the expected substance isolated and identified? Write a lab paper about the experiment and its findings.
Students submit research for competition using techniques covered in the lesson.
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