A compound that moves far up the plate is typically:

A compound that moves far up the plate is typically:

• A. Highly polar
• B. Moderately polar
• C. Large molecular weight
• D. Relatively nonpolar

Answer: (D)

In normal-phase TLC, how far a compound travels depends on its interaction with the polar stationary phase versus its affinity for the mobile phase. Polar compounds bind strongly to the polar surface, so they stay near the origin. Nonpolar compounds interact weakly with the stationary phase and are carried along by the solvent, moving higher up the plate. So a compound that moves far up the plate is typically relatively nonpolar. While very large molecules can diffuse more slowly and might not travel as far, polarity relative to the stationary phase is the main factor determining how far a compound moves.

In normal-phase TLC, how far a compound travels depends on its interaction with the polar stationary phase versus its affinity for the mobile phase. Polar compounds bind strongly to the polar surface, so they stay near the origin. Nonpolar compounds interact weakly with the stationary phase and are carried along by the solvent, moving higher up the plate. So a compound that moves far up the plate is typically relatively nonpolar. While very large molecules can diffuse more slowly and might not travel as far, polarity relative to the stationary phase is the main factor determining how far a compound moves.