Chromatography Practice Test 2026 - Free Chromatography Practice Questions and Study Guide

On a normal-phase plate, the stationary phase is polar and the mobile phase is relatively nonpolar, so polarity largely dictates how far a compound moves: more polar compounds stick to the plate and travel less, while less polar ones move farther. When two compounds have similar polarity, they interact with the polar stationary phase in a very similar way, so they partition between the stationary and mobile phases similarly. This means their migration distances (their Rf values) will be close, and they will travel similar amounts up the plate. If their polarity differed greatly, you would expect noticeably different migration.