AQA GCSE Chemistry RP6: Paper Chromatography of Food Colourings
Setup → solvent rise → mark solvent front → measure in mm → calculate Rf → identify known and unmatched dyes in U.
1. Setup check
2.0 cm
1.0 cm
2.5 mm
Validate the apparatus before starting the chromatogram.
2. Run and mark
The solvent front should stop at about three quarters of the way up the paper.
3. Measurement tools
Use the centre of each spot, not the top edge or bottom edge. Distances are measured from the origin line in mm.
Mark the solvent front before measuring.
4. Identify mixture U
Complete the Rf table first.
Known references: A–D
Unknown: U
Solvent: water
Final solvent distance: 80 mm
Results table
| Spot | Colour | Solvent / mm | Spot / mm | Rf entered | Status |
|---|