Chromatography can be used to separato components of a mixture. a4. (a) A student set up the apparatus without making any errors. The chromatogram in Dlagram 2 shows the student's rosults. Dlagram 2 (i) What do the results tell you about the composition of the black food colouring? __ (ii) Use Diagram 2 to complete Table 1. Table 1 square square (iii) Use your answers in part (b) (ii)to calculate the R value for food colour C. (2) R_(f)value= (1)

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Chromatography can be used to separato components of a mixture. a4. (a) A student set up the apparatus without making any errors. The chromatogram in Dlagram 2 shows the student's rosults. Dlagram 2 (i) What do the results tell you about the composition of the black food colouring? __ (ii) Use Diagram 2 to complete Table 1. Table 1 square square (iii) Use your answers in part (b) (ii)to calculate the R value for food colour C. (2) R_(f)value= (1)

Answer 1

Without the specific distances provided in the question, it's impossible to give a numerical answer. However, the process for answering this question would be: (i) If multiple bands are visible in the chromatogram, this indicates that the black food colouring is a mixture of different substances. (ii) The distances would be measured from the chromatogram and filled in the table. (iii) The \( R_{\mathrm{f}} \) value for food colour C would be calculated using the formula provided.

Answer 2

## Step 1: The first part of the question asks what the chromatogram tells us about the composition of the black food colouring. In chromatography, different components of a mixture will move at different rates, resulting in them separating out into distinct bands on the chromatogram. If multiple bands are visible, this indicates that the substance is a mixture. ## Step 2: The second part of the question asks us to use the chromatogram to complete the table. The distance from the start line to the solvent front is the total distance that the solvent has moved. The distance moved by food colour C is the distance from the start line to the band corresponding to food colour C. ## Step 3: The third part of the question asks us to calculate the \( R_{\mathrm{f}} \) value for food colour C. The \( R_{\mathrm{f}} \) value, or retention factor, is a ratio of the distance moved by a particular component (in this case, food colour C) to the total distance moved by the solvent. ### The formula for calculating the \( R_{\mathrm{f}} \) value is: ### \( R_{\mathrm{f}} = \frac{\text{Distance moved by the component}}{\text{Total distance moved by the solvent}} \)

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