Chromatography

Sometimes a spot will remain on the baseline, where a sample was first applied. Suggest a value for the ${\mathrm{R}}_{\mathrm{f}}$ of this substance.

Sometimes a spot will remain on the baseline, where a sample was first applied. Outline how you could determine whether these materials are pure or a mixture.

Sometimes a spot will remain on the baseline, where a sample was first applied. Suggest what affinity this substance would have for the solvent.

Explain how running the separation too long would affect the ${\mathrm{R}}_{\mathrm{f}}$ of yellow spots?

What will happen to the solvent front eventually if the solution was left for a long time?

Explain why the ${\mathrm{R}}_{\mathrm{f}}$ values for any set of specific conditions used in chromatography are constant. 

Calculate the ${\mathrm{R}}_{\mathrm{f}}$ values for blue coloured spots in the below figure.

Calculate the ${\mathrm{R}}_{\mathrm{f}}$ values for yellow coloured spots in the below figure.

Calculate the ${\mathrm{R}}_{\mathrm{f}}$ values for green coloured spots in the below figure.