In TLC, if origin to spot is 60 mm and origin to solvent front is 150 mm, what is the Rf value?

In TLC, if origin to spot is 60 mm and origin to solvent front is 150 mm, what is the Rf value?

• A. 0.40
• B. 0.30
• C. 0.50
• D. 0.60

Answer: (A)

Rf value is the fraction of the distance the spot has moved relative to the distance the solvent front has moved. It’s calculated by dividing the distance the spot travels by the distance the solvent front travels, giving a unitless number between 0 and 1. Here, the spot has moved two-fifths of the solvent-front distance. Therefore, the Rf value is two-fifths (which corresponds to 0.4). If the movement had been a different fraction, like one-third, one-half, or six-tenths, that would indicate corresponding different distances traveled by the spot relative to the solvent front.

Rf value is the fraction of the distance the spot has moved relative to the distance the solvent front has moved. It’s calculated by dividing the distance the spot travels by the distance the solvent front travels, giving a unitless number between 0 and 1.

Here, the spot has moved two-fifths of the solvent-front distance. Therefore, the Rf value is two-fifths (which corresponds to 0.4).

If the movement had been a different fraction, like one-third, one-half, or six-tenths, that would indicate corresponding different distances traveled by the spot relative to the solvent front.