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?
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Answer
Based on the chromatogram in Figure 4, the mixture that shows no separation and remains at the origin point indicates it contains an insoluble food colouring. In this case, the answer is C mixture R.
Step 2
Give a change that could be made to the experiment to obtain an R_f value for the insoluble colouring.
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Answer
To obtain an R_f value for the insoluble colouring, a possible change to the experiment would be to increase the volume of the solvent used, allowing for a greater contact area and potential for the insoluble food colouring to dissolve.
Step 3
Explain, by referring to Figure 4, which mixture is separated into the greatest number of soluble food colourings by this chromatography experiment.
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Answer
Referring to Figure 4, mixture P shows the highest number of distinct spots, indicating that it has been separated into the greatest number of soluble food colourings during the chromatography experiment. The more distinct spots that appear, the more components are present in the mixture.