New
New
Year 10
AQA
Foundation

Chromatography: paper

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

New
New
Year 10
AQA
Foundation

Chromatography: paper

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

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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.

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.

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.

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

Content guidance

  • Equipment requiring safe usage.

Supervision

Adult supervision recommended.

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).

Video

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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

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