Question

Based on this TLC plate, comment on the substances (CC, RC, PC, CO) Rf values and compare its purity.

Answer 1

Upon the structure of the molecule ,TLC can be used to identify the compounds as well as to separate them.The distance travel by the solvent front and the compound is usually expressed as the Rf values. Rf value= distance traveled by compound ÷ distance travel by solvent front.

The larger an Rf value of a compound ,the larger the distance it travels on TLC plate.when comparing two different compounds run under identical chromatography conditions, the compound with the larger Rf value is less polar because it interacts less strongly with the polar adsorbent on the TLC plate.

In the above TLC plate four different substances show identical Rf values , means four compounds have identical polarity under the same chromatography conditions.That means they are likely ( but not necessarily) the same substances otherwise substances are not pure.