Question

A student chromatographs mixture and after developing the spots with a suitable reagent he observes the following?

. A student chromatographs a mixture, and after developing the spots with a suitable reagent he observe the following: Point of application Solvent front What are the R, values?

Answer 1

Hi!

R_f or Retention Value is defined as the ratio of the distance moved by the solute and the distance moved by the solvent (mobile phase)

R_f or Retention Value is defined as the ratio of the distance moved by the solute and the distance moved by the solvent (mobile phase) R_f = Distance from Baseline traveled by solute/Distance from Baseline to solvent front Every compound have a specific Rf value for every specific solvent and solvent concentration. For that reason, if you have a unknown sample you can compare the Rf value calculated with Rf values of known compounds and discover the compound in your sample. For every dye zone measure the distance from origin(point of application) to the center of the dye zone and also measure the distance from the baseline (point of application) and the solvent front and calculate the Rf value. Because the solvent front is always larger than the distance traveled by the solute, Rf values are always between 0 - 1.

Every compund have a specific Rf value for every specific solvent and solvent concentration. For that reason, if you have a unknow sample you can compare the Rf value calculated with Rf values of known compunds and discover the compound in your sample.

For every dye zone measure the distance from origin(point of aplication) to the center of the dye zone and also measure the distance from the baseline (point of aplication) and the solvent front and calculate the Rf value.

Because the solvent front is always larger than the distance travelled by the solute, Rf values are always between 0 - 1.