1. Thin-layer chromatography may be used to: (circle the letters of all correct answers)
a. monitor the progress of column chromatography of colorless compounds.
b. determine that two organic compounds are different.
c. monitor the progress of an organic reaction.
d. determine that a sample of an organic compound contains impurities.
e. determine conditions to use for a column chromatographic separation.
2. Calculate the Rf values for compounds X, Y and Z on the TLC plate here:
Rf = (distance center of spot travels from the starting line) / (distance solvent front travels from the same line)
Top dashed line shows the solvent front
Bottom dashed line is the starting line
Stationary phase is silica gel
Mobile phase is dichloromethane
Show all calculations and keep two significant figures.
3. On the silica gel TLC plate pictured above, for X, Y and Z, the least polar compound is _______.
4. On a silica gel TLC plate, with CH2Cl2 as the mobile phase, for A, B, and C, the compound with the smallest Rf would be: ___________ and the largest Rf would be: ___________
5. A mixture of two white compounds was separated on a TLC plate. The measured Rf values were 0.25 and 0.65. The mixture was spotted on the 1.0 cm line and the solvent front reached the 8.0 cm line. What was the final distance (in cm) between the centers of the two spots on the developed TLC plate? Show all calculations and keep two significant figures.