S EPARATION BY CHROMATOGRAPHY Describe chromatography as an analytical technique that separates components in a mixture. State that the mobile phase may be a liquid or a gas. State that the stationary phase may be a solid, or either a liquid or solid on a solid support. State that a solid stationary phase separates by adsorption. State that a liquid stationary phase separates by relative solubility.

S TARTER Follow the instructions carefully and have a go at producing your own chromatogram

C HROMATOGRAPHY 1. On your filter paper, draw a pencil line 2 cm from the base of the paper 2. On the pencil line put a small spot of ink/food colouring and leave to dry briefly 3. Pour a small amount of water into a small beaker. Using the glass rod as support, hang the filter paper so it is just touching the surface of the water. 4. Cover carefully and leave until the water has travelled almost to the top of the filter paper 5. Remove the filter paper and mark in pencil the position that the water has reached. 6. Leave to dry

SKETCH Draw a picture of the equipment you used. Label the solvent, chromatogram, solvent front, original position of the sample and positions of the different colour inks. Why is chromatography a useful analytical tool? Can you think of where chromatography might be useful?

TLC As you watch the video, jot down any terms that you think you will need to find out in order to understand chromatography.

GLOSSARY Phase (mobile and stationary) Solvent front Adsorption R f value Chromatogram

P HASES ChromatographyThin layer Stationary phase = SOLID Mobile phase = LIQUID Gas Stationary phase = LIQUID (or solid on a solid support) Mobile phase = GAS

How does chromatography work to separate the different components? Why do different components travel different distances?

S EPARATION

Q UESTIONS Complete question 1 on page 105