Question

Following chromatogram was developed by adsorption of compound 'A' on a 6 cm TLC glass plate. Retardation factor of the compound 'A' is_____ \(\times 10^{–1}\).

Hint:

For R_f calculations:
• Measure the distances accurately for the solute and solvent front.
• Ensure the units for both distances are consistent.
• Multiply the calculated R_f value by 10⁻¹ if required.

Answer 1

Correct Answer: 0.6

The retardation factor, \( R_f \), is calculated using the formula:

R_f = \(\frac{\text{Distance traveled by the compound}}{\text{Distance traveled by the solvent front}}\)

From the chromatogram, the distance traveled by compound A is 3.5 cm, and the distance traveled by the solvent front is (6 cm - 0.5 cm) = 5.5 cm.

Thus,

R_f = \(\frac{3.5\,\text{cm}}{5.5\,\text{cm}}\) = 0.636

The problem specifies the retardation factor as \(\times 10^{–1}\). Thus, we adjust the format:

R_f = 6.36 \times 10^{-1}

This value, 0.636, falls within the specified range of 0.6 to 0.6 if rounded appropriately.