Paper chromatography

2 marks · Easy

In a paper chromatography experiment, the pencil line was drawn 1.0 cm from the bottom of the paper. The solvent front travelled 7.2 cm from the pencil line, and a blue dye moved 5.0 cm from the pencil line. Calculate the R_f value for the blue dye.

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0.69 (±0.01)

Common mistakes: Incorrectly dividing the solvent front by the spot distance

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Marking points

M1 · 1 mark · Correctly applies the formula: R_f = (distance moved by spot)/(distance moved by solvent front).

A1 · 1 mark · Correctly calculates value of 0.69 (to two decimal places). (follow-through)

Worked solution

R_f = (distance moved by dye) / (distance moved by solvent front)