Purity, formulations and chromatography

Medium

A student investigated a green food colouring containing blue and yellow dyes using two different types of chromatography paper, Paper P and Paper Q.

The table below shows the results of the experiment:

Chromatography Paper	Dye	Distance moved by dye ( $cm\text{cm}$ )	Distance moved by solvent ( $cm\text{cm}$ )	$R_f$ value
Paper P	Blue	4.5	15.0	0.30
Paper P	Yellow	10.5	15.0	0.70
Paper Q	Blue	6.0	15.0	0.40
Paper Q	Yellow	$d$	15.0	0.75

Calculate the distance moved by the yellow dye on Paper Q, represented by $d$ .

[2]

Explain which chromatography paper (Paper P or Paper Q) has a stronger attraction to the blue dye, using the $R_f$ values from the table.

[2]

Purity, formulations and chromatography Questions