What is chromatography?

Chromatography is a chemical analysis technique, used to separate substances in a mixture.

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What is paper chromatography used for?

To separate a mixture of substances based on their solubility in a solvent.

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What is the name given for the pencil line in paper chromatography?

The baseline.

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When doing paper chromatography, why should we use pencil for the baseline rather than pen?

Pen ink would dissolve in the solvent and move up the paper.

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What are the 2 phases of chromatography?

1Mobile phase - in which molecules can move, usually a liquid or gas.


2Stationary phase - in which molecules can't move, usually a solid or really thick liquid.

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When doing paper chromatography, what determines the amount of time molecules spend in the mobile and stationary phases?

  1. How soluble they are in the solvent (mobile phase).
  2. How attracted they are to the paper (stationary phase).

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When doing paper chromatography, what happens to chemicals that have greater solubility in the mobile phase?

A substance which is more soluble in the mobile phase will spend more time in the mobile phase.


This means it will move faster, and therefore travel a further distance up the paper than a less soluble chemical.

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What is the formula to calculate an Rf value from a chromatogram?

Rf​ = distance travelled by the solventdistance travelled by the substance​

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