Chemical Analysis Required Practicals

Chromatography Practical

1

Preparing the paper

1. On a piece of chromatography paper, draw a horazontal pencil line 2cm from the bottom
2. Using a Capillary Tube, put small spots of each food colouring onto the pencil line, ensuring that they are at least 1cm apart
3. Label the four known dyes A - D, and the unknown dye U

Safety Concerns

• Food colouring can be irritative

2

Separating mixtures

1. Take a beaker and fill it with about 1cm³ of water
2. Suspend the chromatography paper in the beaker so that the bottom edge of the paper is dipped in the water
3. Wait for the water solvent to travel up about 3/4 of the paper, then remove it and hang it up to dry it
4. Calculate the Rf values for each spot.
   $\mathrm{Rf\; value}=\frac{\mathrm{Disance\; travelled\; by\; solute}}{\mathrm{Distance\; travelled\; by\; solvent}}$

Safety Concerns

• Glass can smash