Purity, formulations and chromatography

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Question 12
Medium

A student performs a paper chromatography experiment to analyze a mixture of pigments extracted from a green leaf.

The student obtains the following measurements:

  • Distance from the starting line to the solvent front: 8.5 cm8.5\text{ cm}8.5 cm
  • Distance from the starting line to the center of the yellow-green spot: 3.4 cm3.4\text{ cm}3.4 cm
  • Distance from the starting line to the center of the blue-green spot: 5.1 cm5.1\text{ cm}5.1 cm
a.

Calculate the RfR_fRf​ values for both the yellow-green and the blue-green spots.

[3]
b.

Identify the stationary phase and the mobile phase in this chromatography experiment.

[2]
c.

A second student repeats this experiment under identical conditions but uses a different solvent, leading to different RfR_fRf​ values for the same pigments. Explain why changing the solvent changes the RfR_fRf​ values.

[3]

Purity, formulations and chromatography Questions

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