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      Chromatography

      I can describe how chromatography works and use a chromatogram to answer questions about a substance.

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      Lesson 7 of 7
      New
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      • Year 7

      Chromatography

      I can describe how chromatography works and use a chromatogram to answer questions about a substance.

      Lesson details

      Key learning points

      1. Chromatography can be used for both separation of minute samples and analysis.
      2. A pure substance will only produce one spot on a chromatogram.
      3. A mixture will produce many spots on a chromatogram.
      4. Comparing chromatograms can help to identify an unknown component in a sample.
      5. Pencil is insoluble in water.

      Keywords

      • Solvent - A solvent is a liquid into which a solute dissolves.

      • Soluble - When a substance dissolves in a liquid, it is described as soluble in that liquid.

      • Chromatography - Chromatography is a technique that separates a mixture into its different parts and the results can be analysed.

      • Chromatogram - A chromatogram is the resultant pattern on the stationary phase after chromatography has been carried out.

      • Compare - To compare is to look for similarities and/or differences between two objects or ideas.

      Common misconception

      Pupils can struggle to interpret information that contain several samples on one chromatogram.

      Stress a systematic approach to interpreting chromatograms - use rulers. Live model this - using a visualiser helps enormously.

      Create a mini-crime scene (e.g. stolen plant with a ransom note) and have pupils conduct chromatography on different pens to identify who wrote the note. Don't forget to make a chromatogram of the ransom note pen beforehand to use for comparison!
      Teacher tip

      Equipment

      Content guidance

      • Risk assessment required - equipment

      Supervision

      Adult supervision required

      Licence

      This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

      Lesson video

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      Prior knowledge starter quiz

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      6 Questions

      Q1.
      If you have a mixture of sand and salt, adding water will dissolve the salt. What will happen to the sand?

      It will dissolve.
      Correct answer: It will sink to the bottom of the container.
      It will evaporate out of the container.

      Q2.
      A substance that dissolves in a solvent is said to be in that solvent.

      Correct Answer: soluble

      Q3.
      Match the word with the definition.

      Correct Answer:Absorb,Ability of a substance to take in another substance.
      Correct Answer:Solute,A substance that can dissolve in a liquid.
      Correct Answer:Solvent,A liquid in which a solute dissolves.
      Correct Answer:Sample,A substance which will be tested in an investigation.
      Correct Answer:Miscible,Ability of a liquid to dissolve/mix in another liquid.

      Q4.
      Order the following steps describing how to make a solution.

      1 - If necessary, crush the solute into small pieces.
      2 - Add the solute to the solvent.
      3 - Stir to dissolve the solute.
      4 - Filter the mixture to remove any undissolved solute.

      Q5.
      Oil and water are two liquids that cannot mix. They are said to be ...

      Correct Answer: immiscible

      Q6.
      Which of the following substances are mixtures?

      Correct answer: Pure orange juice
      Copper sulfate
      Correct answer: Ink
      Oxygen
      Correct answer: Tap water

      Assessment exit quiz

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      6 Questions

      Q1.
      What is chromatography used for?

      To mix coloured substances together.
      Correct answer: To separate and analyse coloured mixtures.
      To create coloured solutions.

      Q2.
      The pattern of results obtained from chromatography is called a ...

      Correct Answer: chromatogram, chromatogram.

      Q3.
      How does a pure substance behave in chromatography?

      It produces multiple spots.
      It does not move.
      Correct answer: It produces one spot only.

      Q4.
      The line on the chromatogram on which the samples are placed must be drawn in pencil because it is in the solvent.

      Correct Answer: Insoluble

      Q5.
      Order these steps in performing chromatography, starting with drawing a pencil line.

      1 - Draw a pencil line 1 cm up from the bottom of a piece of chromatography paper.
      2 - Carefully add a small drop of your sample to the pencil line.
      3 - Place a small volume of solvent in a beaker, lower than 1cm depth.
      4 - Wind your paper on a support so that the pencil line will be above the solvent.
      5 - Lower your paper vertically into the beaker so it just touches the solvent.
      6 - Leave to allow the solvent to absorb up the paper and separate your sample.
      7 - Remove and allow to dry.

      Q6.
      What can you conclude from this chromatogram?

      An image in a quiz
      Dye A contains three substances.
      Correct answer: Dye B is insoluble in the solvent used.
      Correct answer: Dye C contains only one substance.
      Correct answer: Dye A is a mixture.
      Dye C contains the most soluble substance.

      Lesson appears in

      UnitScience / Separation techniques

      Science

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