Lesson 4 - Paper Chromatography

Question 1

When is chromatography used?

Answer 1

Paper chromatography is a technique for separating components of a mixture

Question 2

Chromatography

Answer 2

Inks, paints and foods often contain mixtures of coloured compounds . Chromatography is used to find out which coloured compounds a mixture contains

Question 3

How Does it Work

Answer 3

The dyes/inks are soluble in water (or whichever solvent you are using) and they are carried up the paper with it.
More soluble compounds are carried up the paper faster than less soluble compounds. This causes them to separate out.

Question 4

Calculating Rf values

Answer 4

A chemical can also be identified by its Rf (Retention Factor)
It is the ratio of the distance travelled by the sample (spots) to the distance travelled by the solvent (water).

The formula is:
Rf = distance moved by sample/ distance moved by solvent