Contents
Key Stage 4
Meaning
The Retention Factor is a ratio of how far a chemical moves along the paper compared to how far the solvent moves along the paper in a chromatography experiment.
About Retention Factors
- Each chemical has a Retention Factor (Rf number).
- The larger the Retention Factor the greater the force of attraction experienced by the chemical to the paper. The chemical is 'retained' in place.
- Rf numbers are unique to each chemical and can be used to separate and identify the chemical.
Equation
Retention Factor = (distance moved by chemical)/(distance moved by solvent)
\(R_f = \frac{d_c}{d_s}\)
Where:
Rf = Retention Factor
dc = distance moved by the chemical
ds = distance moved by the solvent