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3.2 Methods of separating and purifying substances

3.2 Methods of separating and purifying substances

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Question 38

Thin-layer chromatography (TLC) can be used to separate and identify the different photosynthetic pigments found in a spinach leaf extract.

Six steps for carrying out this TLC experiment are listed below, but they are not in the correct order.

  1. Place the TLC plate into the developing chamber, ensuring the solvent level is below the start line, and cover with a lid.
  2. Draw a start line in pencil 1.5 cm from the bottom of the TLC plate.
  3. Remove the TLC plate from the chamber just before the solvent front reaches the top and immediately mark the solvent front with a pencil.
  4. Pour a small volume of the mobile phase solvent into the developing chamber and cover it with a watch glass.
  5. Use a capillary tube to apply a small, concentrated spot of the leaf extract on the pencil start line and let it dry.
  6. Leave the covered chamber undisturbed as the solvent travels up the plate.

List the remaining steps in the correct order to complete the sequence.

The first two steps have been determined for you.

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Markscheme

3.2 Methods of separating and purifying substances Questions

  1. GCSE
  2. /Chemistry
  3. /3.2 Methods of separating and purifying substances

107 exam-style questions on Edexcel GCSE Chemistry 3.2 Methods of separating and purifying substances, covering 3.2.1 Pure substances and mixtures, 3.2.2 Techniques for separating mixtures, 3.2.3 Paper chromatography and Rf values, and 3.2.4 Making water potable. Each one has a worked solution and a mark scheme showing where the marks go.

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