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Year 10
AQA
Higher

Chromatography: paper

I can describe how paper chromatography works and use chromatograms to classify substances as pure or a mixture.

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New
New
Year 10
AQA
Higher

Chromatography: paper

I can describe how paper chromatography works and use chromatograms to classify substances as pure or a mixture.

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Share activities with pupils
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Lesson details

Key learning points

  1. Chromatography has two phases, stationary and mobile, and separation depends on the distribution between these phases.
  2. Both aqueous and non-aqueous solvents can be used in chromatography.
  3. Chromatograms can be used to identify pure and impure substances.

Keywords

  • Chromatography - Chromatography is a technique that separates the components of a mixture, and the results can be analysed.

  • Mobile phase - The mobile phase is the movement of a solvent and any dissolved components of a sample along the stationary phase in chromatography.

  • Stationary phase - The stationary phase is a surface along which the solvent (and any dissolved components) travels. It does not move during chromatography.

  • Chromatogram - A chromatogram is the resultant pattern of a sample’s components on the stationary phase after chromatography has been carried out.

Common misconception

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

Stress a systematic approach to interpreting chromatograms (i.e. use rulers). Live modelling this using a visualiser helps enormously.

Pre-make chromatograms of pure and impure samples and challenge pupils to identify the pure components of the impure samples.
Teacher tip

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), 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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Starter quiz

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6 Questions

Q1.
What is the role of a solvent in a solution?
Correct answer: to dissolve the solute
to react with the solute
to solidify the solute
to reduce the solute's temperature
to increase the solute's mass
Q2.
Which term describes a substance that cannot be dissolved in a particular solvent?
soluble
Correct answer: insoluble
solubility
solution
solute
Q3.
How does increasing the temperature of a substance generally affect the solubility of a solid in a liquid?
Correct answer: increases it
decreases it
does not affect it
Q4.
Match the separation technique to its most likely use.
Correct Answer:filtration,separating a liquid from an insoluble solid

separating a liquid from an insoluble solid

Correct Answer:distillation,separating liquids with different boiling points

separating liquids with different boiling points

Correct Answer:evaporation,recovering a dissolved solid from a solution

recovering a dissolved solid from a solution

Correct Answer:decanting,removing a liquid layer from a mixture

removing a liquid layer from a mixture

Q5.
Match the property to the type of mixture.
Correct Answer:uniform composition (e.g. sugar water),solution

solution

Correct Answer:layers form (e.g. oil and water),a mixture of immiscible liquids

a mixture of immiscible liquids

Correct Answer:particles settle (e.g. flour and water),suspension

suspension

Q6.
A solution in which more solute can be dissolved is described as ...
Correct Answer: unsaturated

Exit quiz

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6 Questions

Q1.
What is the main purpose of chromatography?
to change the composition of a mixture
Correct answer: to separate the components of a mixture
to increase the temperature of a mixture
to measure the volume of a mixture
to observe the colour changes in a mixture
Q2.
Match the following terms with their correct descriptions:
Correct Answer:chromatography,a technique that separates the components of a mixture

a technique that separates the components of a mixture

Correct Answer:mobile phase,the movement of a solvent and dissolved sample components

the movement of a solvent and dissolved sample components

Correct Answer:stationary phase,a surface along which the solvent travels and does not move

a surface along which the solvent travels and does not move

Correct Answer:chromatogram,the resultant pattern of a sample’s components after chromatography

the resultant pattern of a sample’s components after chromatography

Q3.
When analysing a chromatogram, what indicates that a substance is pure?
multiple spots of different colours
Correct answer: a single, distinct spot
no visible spots
spots that merge together
spots spread evenly across the chromatogram
Q4.
What is produced at the end of the chromatography process?
Correct Answer: chromatogram
Q5.
Order the following steps of paper chromatography correctly.
1 - Cut the chromatography paper to size.
2 - Draw a starting line (in pencil).
3 - Apply the sample(s) to the paper.
4 - Place the paper in a solvent.
5 - Wait for the solvent to travel up the paper.
6 - Observe the chromatogram.
Q6.
In chromatography, if a mixture contains three different components, how many distinct spots should you expect on the chromatogram?
Correct Answer: 3, three