Question

Using the given figure, the ratio of $R_f$ values of sample A and sample C is x × 10–2. Value of x is __________.

Answer 1

The $R_f$ value in chromatography is given by:
$R_f = \frac{\text{Distance traveled by the sample spot}}{\text{Distance traveled by the solvent front}}.$
Step 1: Calculate $R_f$ for sample $A$
For sample $A$:
$R_f(A) = \frac{\text{Distance traveled by sample } A}{\text{Distance traveled by solvent front}} = \frac{5}{12.5}.$
$R_f(A) = 0.4.$
Step 2: Calculate $R_f$ for sample $C$
For sample $C$:
$R_f(C) = \frac{\text{Distance traveled by sample } C}{\text{Distance traveled by solvent front}} = \frac{10}{12.5}.$
$R_f(C) = 0.8.$
Step 3: Calculate the ratio of $R_f$ values
The ratio of $R_f$ values for sample $A$ and sample $C$ is:
$\text{Ratio} = \frac{R_f(A)}{R_f(C)} = \frac{0.4}{0.8} = 0.5.$
Expressing the ratio as $x \times 10^{-2}$:
$\text{Ratio} = 50 \times 10^{-2}.$
Final Answer: $x = 50$.