This exam focus covers Exam Focus within Chromatography for GCSE Chemistry. Revise Chromatography in Chemical Analysis for GCSE Chemistry with 20 exam-style questions and 15 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 11 of 13 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 11 of 13
Practice
20 questions
Recall
15 flashcards
🎯 Exam Focus
Very High Frequency
What Examiners Ask About Chromatography
- Calculate an Rf value from given distance data (1–2 marks) — show formula and working
- Describe the method for paper chromatography (3–4 marks)
- Interpret a chromatogram — how many substances? Which samples match? (2–3 marks)
- Explain why pencil is used instead of pen (1 mark)
- Explain why the start line must be above the solvent (1 mark)
- Explain why substances separate — different solubilities / affinities for phases (2 marks)
AO3 Evaluation Tips
- Limitations: different substances can have the same Rf; colourless substances need UV detection or chemical developers
- Improving accuracy: spot size, correct solvent choice, maintaining consistent conditions