A dye spot moves 5.4 cm from the baseline while the solvent front moves 7.2 cm. Calculate Rf.
[2 marks]
Total for this question: 2
All calculations
Chromatography Rf
Chemical analysis
AQA 8462
ORIGINAL
Rf = distance moved by substance / distance moved by solvent
Both distances start at the pencil baseline, and the solvent front always goes underneath the fraction.
Board and spec code confirmed against AQA 8462 · registry checked 2026-07-17How this checking works
Work it, then mark it
Do each calculation on paper first, then reveal the mark scheme and tick the marks you actually earned — the same way you should mark past papers.
Q1
Do the calculation on paper first — then mark it.
Where the marks get lost
- Measuring from the bottom of the paper instead of the baseline.
- Giving Rf a unit or obtaining a value above 1.
Exam tip: Rf has no unit and must lie between 0 and 1 for a spot that remains below the solvent front.
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