Question
Describe how to carry out paper chromatography to separate the pigments in a food colouring dye. [5]
Mark scheme — any five:
- Draw a pencil baseline on chromatography paper (not pen — ink would run) (B1)
- Place a small concentrated spot of the dye on the baseline (B1)
- Allow to dry; repeat spotting to concentrate (B1)
- Place paper in a solvent (e.g. ethanol/water) ensuring solvent level is BELOW the baseline (B1)
- Allow solvent to rise up the paper until near the top; remove (B1)
- Mark the solvent front position immediately; measure distances (B1)
- Calculate Rf values for each spot (B1) [Max 5]
5 marks · take your time before peeking.
Sign up to try the next 30 problems
Save your streak, mark answers against the spec, and build a daily revision habit. Free during public beta — no card, no auto-renew.
Generated by TopMyGrade AI · cross-check official sources before relying on the mark-scheme phrasing.