Which of the following R_f values is not possible?

The correct answer is 2.0.

Key Points

• The ratio of the distance travelled by the analyte to the distance travelled by the solvent front on a chromatogram is known as the retardation or retention factor (R_f) value.
• R_f = Distance travelled by analyte / Distance travelled by solvent front.
• In chromatographic techniques, the mobility of analytes with mobile solvents is different from the mobility of analytes added to stationary phases (phases).
• This discrepancy is explained by the different affinities of analytes for stationary and mobile solvents.
• The longer an analyte remains in a stationary phase, the lower the R_f value it will have, and the opposite is also true.
• R_f values are the ratios of solute (analyte) migration distances to solvent fronts, they are always less than one.
• Because solutes must have some attractive qualities with stationary phases, the solvent front always travels more than the solute front.
• R_f values will always be between 0 and 1 because the denominator has a greater value.

Therefore, the correct answer is 2.0.