This experiment introduces students to thin layer chromatography
as a means of studying intermolecular forces. After a discussion of
the principles of TLC methodology, intermolecular forces between
solvent and solute molecules, and the roles of stationary and
mobile phases, the experiment turns to the specific cases of
acetylsalicylic acid, acetaminophen, and caffeine for solutes and
ethanol, ethylacetate, and cyclohexane for solvents. The student
makes runs of each of the three solutes side-by-side in each of the
solvents, recording the Rf factors for each case. Then
an unknown of one of the three solutes is given to the student to
investigate and identify. The student is asked to discuss
observations in terms of intermolecular forces.
- Become familiar with the methodology and practice of TLC.
- Learn how to the Rf factor by measuring spot
movement on developed plates.
- Be able to compare Rf factors from runs with knowns
with values for unknown runs.
- Be able to answer questions about the method and observed
behavior of solute-solvent interactions.