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P, Q, R and S are mixtures of food colourings - Edexcel - GCSE Chemistry - Question 3 - 2016 - Paper 1
Question 3
P, Q, R and S are mixtures of food colourings. They are investigated using paper chromatography. Figure 4 shows the chromatogram at the end of the experiment. (i) W... show full transcript
Worked Solution & Example Answer:P, Q, R and S are mixtures of food colourings - Edexcel - GCSE Chemistry - Question 3 - 2016 - Paper 1
Step 1
Which mixture contains an insoluble food colouring?
Answer
Based on the chromatogram provided in Figure 4, the mixture that shows no movement from the baseline indicates the presence of an insoluble food colouring. In this case, mixture S has not moved, thus it contains the insoluble food colouring.
Step 2
Give a change that could be made to the experiment to obtain an Rf value for the insoluble colouring.
Answer
To obtain an Rf value for the insoluble colouring, one change would be to use a solvent that can dissolve the food colouring. This may involve selecting a more effective solvent to ensure the insoluble colouring can dissolve and hence allow for measurement of its Rf value.
Step 3
Explain, by referring to Figure 4, which mixture is separated into the greatest number of soluble food colourings by this chromatography experiment.
Answer
Referring to Figure 4, mixture Q displays the most spots above the baseline, indicating the presence of multiple soluble food colourings. The dispersal of these spots suggests that mixture Q has the greatest diversity of soluble components among the mixtures tested.