Learning objective

Calculate and interpret Rf values.

Read the explanation, check the common trap, then practise with flashcards and questions.

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At a glance

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Topic

Chromatography (A-level only)

Subtopic

Chromatography (A-level only)

AQA A Level ChemistryOrganic chemistry

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Understand this objective

Short explanation

Calculate and interpret Rf values. sits within Chromatography (A-level only) for Chromatography (A-level only) in AQA A-Level Chemistry 7405. A strong exam response should identify the relevant chemical relationship, choose the correct formula or representation where needed, substitute values or evidence carefully, and state the final conclusion with appropriate units or terminology. When revising this objective, focus on the distinction between the concept being tested and neighbouring ideas so that calculation steps, organic representations, or equilibrium reasoning do not collapse into a generic answer.

Key concepts

Rf valuestationary phasemobile phase

Why it matters

This objective helps connect Chromatography (A-level only) to exam-style questions, flashcards, and revision notes for Chromatography (A-level only).

Common mistakes

2 linked

Incorrect Rf Value Calculation: Always measure the distance from the baseline to the centre of the spot for the substance and divide it by the distance travelled by the solvent front.
Misinterpretation of Rf Values: Remember that a higher Rf value indicates that the substance is less polar and interacts less with the stationary phase, moving further with the mobile phase.

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