Mixtures of substances can be separated using different techniques - Edexcel - GCSE Chemistry - Question 4 - 2019 - Paper 1

Another mistake in Figure 5 is that the water outlet is positioned too low, preventing effective collection of distilled water.

The correct order of the steps is: 1 (leave the solvent to rise up the paper), 3 (draw a start line on the piece of paper), 4 (place the paper in the beaker), 5 (remove the paper when the solvent is near the top), 6 (put small spots of the food colourings on the start line).

Food colouring T contains the greatest number of coloured substances, as it exhibits the most spots on the chromatogram indicating multiple separated components.

The R_f value can be calculated using the formula:

$R_f = \frac{distance\ moved\ by\ substance}{distance\ moved\ by\ solvent}\text{ .}$ Substituting the values, we get:

$R_f = \frac{2.30\ cm}{8.00\ cm} = 0.2875\text{ .}$ R_f value to two significant figures is 0.29.