Common Misconceptions

⚠️ Common Misconceptions

Misconception 1: "The spot that travels furthest is the most concentrated"

Wrong. The distance a spot travels is determined by the substance's relative solubility in the solvent and its affinity for the paper — not by how concentrated it is. A very dilute solution of a highly soluble dye will still travel further than a concentrated solution of a less soluble dye. Spot intensity (darkness) is a rough guide to relative concentration, not travel distance.

Misconception 2: "One spot always means a pure substance"

One spot is strong evidence for purity, but it is not definitive. Two different compounds could happen to have the same Rf value in a particular solvent and appear as one spot. To confirm purity, you would need to run the chromatography in a different solvent — if the spot remains single, it is more likely to be pure.

Misconception 3: "Rf values can be greater than 1"

Impossible. A substance cannot travel further than the solvent that is carrying it. The Rf value is always between 0 and 1. If your calculation gives a value above 1, you have measured distances incorrectly — likely measuring substance distance from the wrong point.