1. T HIN - LAYER CHROMATOGRAPHY State that the mobile phase in TLC is a liquid and that the stationary phase is a solid on a solid support. State that the solid stationary phase in TLC separates by adsorption. Explain the term: R f value, and interpret chromatograms in terms of R f values.

2. RECAP On a post it note, write down a key word on chromatography and its definition

3. TLC Use the text book to help you answer these questions 1. In TLC, what is used as the stationary phases and what as the mobile phase? 2. How is the chromatogram produced? 3. What is a chromatogram? 4. Why must the level of the solvent be below the sample spot? 5. Why does the jar containing the TLC plate need to be sealed? 6. What is adsorption? 7. How long is the TLC plate left in the solvent for? 8. Why do the components of the sample travel for different distances? 9. How can you ‘develop’ the chromatogram? 10. How do you interpret a TLC chromatogram?

4. R UNNING A TLC CHROMATOGRAM

5. R F VALUES TLC chromatograms can be interpreted in terms of R f values. This shows how far the component has moved compared to the solvent front. R f = distance moved by component distance moved by solvent front R f values of components can also be compared to those of pure compounds which can help indentify unknown substances.

6. C ALCULATE THE R F VALUES Measuring R f values – for the green spot, x = 1.65 cm and y = 4.85 cm.

7. QUESTIONS Complete question 2 on page 79 and question 2(a) on page 105

8. LIMITATIONS What might some of the limitations for TLC? Brainstorm in pairs some of your ideas