Question

Calculate the Rf value of compounds X and Y based on information (X travels 0.5.0 cm, Y travels 1.0 cm from the origin line; the solvent front is 3.0 cm). Comment on the polarity and separation of X and Y on the TLC plate.

Answer 1

Retention factor or
`R_f` value is defined as the ratio of distance traveled by the unknown to the distance traveled by the solvent front.

`R_f=\frac{\text{ distance by unknown}}{\text {distance by solvent}}`

Putting in the values we get:

`R_f_(X)=(0.50cm)/(3.0cm)=0.16`

`R_f_(Y)=(1.0cm)/(3.0cm)=0.33`

As the
`R_f` value of Y is more than X , it follows that Y compound will be retained less strongly than the compound X. Thus Y is more polar than X.