Retention Factor (Rf)

Key term for OCR GCSE Chemistry A, used in Purity and separating mixtures.

Definition

A numerical value used to identify substances in chromatography, calculated as: $R_f = \frac{\text{distance moved by substance}}{\text{distance moved by solvent front}}$ .

Exam Context

Retention Factor (Rf) appears in OCR GCSE Chemistry A revision content for Elements, compounds and mixtures, especially Purity and separating mixtures and Selecting Purification Methods.

Elements, compounds and mixtures Purity and separating mixtures Selecting Purification Methods

Found in Revision Notes

Elements, compounds and mixtures

Selecting Purification Methods

Purity and separating mixtures • Selecting Purification Methods

Revise note

Related Key Terms

Chromatography Crystallisation Distillate Evaporation

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distance moved by solvent front

distance moved by substance

Filtrate

Filtration

Fraction

Fractional Distillation