Question

Calculate retardation factor (Rf) for two compounds separated by TLC and state which of the two are likely to be polar. (Explain your answer).

Solvent front = 6.5 cm, Distance of A = 5.0 cm, Distance of B = 3.5 cm

Answer 1

Retardation factor (Rf) is calculated using the following formula:

Retardation factor (Rf) = (Distance travelled by solute front)/(Distance travelled by the solvent front)

So,

Given,

Solvent front = 6.5 cm, Distance of A = 5.0 cm, Distance of B = 3.5 cm

Using the above formula:

Rf for compound A = (5.0 cm)/(6.5 cm) = 0.769

Rf for compound B = (3.5 cm)/(6.5 cm) = 0.538

Hence,  the retardation factor (Rf) for compound A is 0.769 and compound B is 0.538.

As we know that higher the polarity of a compound lower will be the retardation factor of that compound and vice-versa. Hence, compound B is likely to be more polar than that of compound A.

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