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This question is about paper chromatography - AQA - GCSE Chemistry - Question 3 - 2021 - Paper 2
Question 3
This question is about paper chromatography. A food colouring contains a dye. Plan an investigation to determine the Rf value for the dye in this food colouring. R... show full transcript
Worked Solution & Example Answer:This question is about paper chromatography - AQA - GCSE Chemistry - Question 3 - 2021 - Paper 2
Step 1
Plan an investigation to determine the Rf value for the dye in this food colouring.
Answer
To determine the Rf value for the dye in the food coloring, follow these steps:
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Prepare the Chromatography Paper:
- Draw a pencil line near the bottom of the chromatography paper.
- Place a small spot of the food coloring on this line.
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Set Up the Beaker:
- Fill a beaker with a suitable solvent (e.g., water or alcohol).
- Ensure the solvent level is below the pencil line on the chromatography paper.
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Assemble the Apparatus:
- Place the chromatography paper into the beaker, ensuring it stands upright and the dye spot is above the solvent level.
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Allow the Solvent to Travel:
- Cover the beaker with a lid to prevent evaporation.
- Wait for the solvent to travel up the chromatography paper until it nearly reaches the top.
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Mark the Solvent Front:
- Once the solvent has traveled, mark the highest point it has reached on the paper (the solvent front).
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Dry the Paper:
- Remove the paper from the beaker and allow it to dry.
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Measure Distances:
- Measure the distance from the start line to the center of the dye spot.
- Measure the distance from the start line to the solvent front.
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Calculate Rf Value:
- Use the formula (R_f = \dfrac{\text{distance moved by substance}}{\text{distance moved by solvent}}) to determine the Rf value.
Step 2
Step 3