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Chromatography (A-level only)
This A-level-only topic uses separation techniques to analyse chemical mixtures.
4
Objectives
10
Flashcards
10
Questions
88 min
Study time
AqaA LevelChemistryOrganic chemistry
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Syllabus checklist
What you need to know
4 objective pages available
Chromatography (A-level only)4 objectives
- Explain separation using stationary and mobile phases.
- Calculate and interpret Rf values.
- Interpret chromatograms and retention times.
- Use chromatography evidence with spectroscopic data in analysis.
Key terms
Stationary PhaseMobile PhaseChromatographySolvent frontThin-Layer Chromatography (TLC)Retention Factor (Rf)
Exam tips
- Understand Rf Values: Always calculate Rf values carefully and remember that they are unitless.
- Double-check your Rf calculations: Before finalizing your answer, verify that you have used the correct distances for both the compound and the solvent front.
Common mistakes
- Confusing stationary and mobile phases: Remember that the stationary phase does not move and is responsible for the interaction with the analytes, while the mobile phase is what carries the analytes through the system.
- Incorrect Rf value calculation: Always ensure to use the distance traveled by the compound in the numerator and the distance traveled by the solvent front in the denominator.
Practice preview
- Which of the following statements correctly describes the role of the stationary phase in chromatography?
- Explain how the choice of mobile phase can affect the separation of components in chromatography.
- A mixture of two dyes is separated using paper chromatography. The Rf value for dye A is 0.6 and for dye B is 0.3. If the solvent front moved 10 cm, calculate the distance traveled by each dye.
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