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Difficulty: MediumPaper and Column Chromatography

During a paper chromatography experiment to analyze a natural dye extract, a component spot migrated 4.8 cm4.8\text{ cm} from the origin line, while the solvent front traveled a total distance of 12.0 cm12.0\text{ cm} from the origin line. What is the retention factor (RfR_f) of this component?

  1. 0.400.40Answer
  2. B
    2.502.50
  3. C
    0.600.60
  4. D
    0.800.80

Answer

The retention factor (RfR_f) of the component is 0.400.40.
The retention factor (RfR_f) is dimensionless and measures the relative mobility of a solute compared to the solvent front. It is calculated using the expression Rf=distance moved by solutedistance moved by solvent frontR_f = \frac{\text{distance moved by solute}}{\text{distance moved by solvent front}}. Substituting 4.8 cm4.8\text{ cm} and 12.0 cm12.0\text{ cm} yields 0.400.40.

Step-by-Step Solution

1
Identify the given values from the chromatographic analysis.
Distance moved by solute spot (dsolute)=4.8 cmd_{\text{solute}}) = 4.8\text{ cm}; Distance moved by solvent front (dsolvent)=12.0 cmd_{\text{solvent}}) = 12.0\text{ cm}.
These measurements are required to calculate the retention factor.
2
Apply the retention factor (RfR_f) formula.
Rf=dsolutedsolvent=4.8 cm12.0 cm=0.40R_f = \frac{d_{\text{solute}}}{d_{\text{solvent}}} = \frac{4.8\text{ cm}}{12.0\text{ cm}} = 0.40.
The retention factor is defined as the ratio of solute displacement to solvent displacement relative to the origin line.

Key Concept

Retention factor (RfR_f) calculation in paper chromatography
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Topics

Paper and Column Chromatography

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