Question

A dye was allowed to undergo migration on a chromatographic paper using a solvent. The dye, and the solvent-front migrated 5 and 20 cm, respectively, from the point of origin. The retention factor (rounded off to two places decimal) for the dye is ________.

Hint:

The retention factor \( R_f \) is a ratio of the distance travelled by the compound to the distance travelled by the solvent-front. It is a measure of the compound's affinity for the stationary phase.

Answer 1

Correct Answer: 0.25

The retention factor \( R_f \) in chromatography is given by the formula: \[ R_f = \frac{\text{Distance travelled by the dye}}{\text{Distance travelled by the solvent-front}}. \] From the question, the dye travels 5 cm, and the solvent-front travels 20 cm. Substituting these values: \[ R_f = \frac{5}{20} = 0.25. \] Thus, the retention factor for the dye is \( \boxed{0.25} \).