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This question is about chromatography of food colouring - AQA - GCSE Chemistry: Combined Science - Question 3 - 2019 - Paper 2
Question 3
This question is about chromatography of food colouring. 0.3.1 Food colouring is a formulation. What is a formulation? A formulation is a mixture designed as a us... show full transcript
Worked Solution & Example Answer:This question is about chromatography of food colouring - AQA - GCSE Chemistry: Combined Science - Question 3 - 2019 - Paper 2
Step 1
Step 2
Explain how paper chromatography separates the dyes in a food colouring.
Answer
In paper chromatography, dyes are distributed differently between the stationary and mobile phases. This happens because different dyes have different solubilities, leading to varying forces of attraction to the stationary phase (the paper) and the mobile phase (the solvent). As a result, the dyes move up the paper at different speeds or rates.
Step 3
Step 4
Explain how the student could use chromatography to identify unknown dyes in the food colouring.
Answer
To identify unknown dyes, the student can run known dyes and food colouring as a chromatogram, comparing the distances moved or the R values. This way, they can identify which unknown dyes are present by comparing their R values to known standards.