Rf formula: "Rf = substance over Front"
Rf = distance by Substance ÷ distance by solvent Front
The capital S on top, capital F on bottom — "Substance over Front"
For what moves where: "More Soluble = Sprints further up"
For phases: "Mobile MOVES, Stationary STAYS"
Quick Check: A student runs chromatography on a suspected food dye and gets three spots. What does this tell them?
The food dye is a mixture — it contains at least three different coloured compounds. It is not a pure substance.
This memory aid covers Memory Aid within Chromatography for GCSE Chemistry. Revise Chromatography in Chemical Analysis for GCSE Chemistry with 23 exam-style questions and 15 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 9 of 13 in this topic. Use it for quick recall, then test yourself straight afterwards so the memory aid becomes usable in an answer.
Practice questions for Chromatography
What is the purpose of chromatography?
Explain how a chromatogram can be used to determine whether a substance is pure or a mixture.