Practical questions

You will complete eight required core practical activities if you are studying GCSE Chemistry, and 18 if you are studying GCSE Combined Science (five of these are in Chemistry).

You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.

There is one core practical activity in the 'States of matter and mixtures' section:

  • Investigate the composition of inks using simple distillation and paper chromatography.

Sample question 1 - Foundation

Question

Mixtures of coloured substances can be separated by paper chromatography.

Give a reason why the start line is drawn in pencil rather than in ink. [1 mark]

Edexcel question courtesy of Pearson Education Ltd.

  • Pencil is insoluble in the solvent (but chromatography would separate the ink in an ink line). [1]

Sample question 2 - Foundation

Question

A student investigates mixtures of food colourings using paper chromatography. One of the substances in a food colouring does not move during the experiment.

Explain one change that could be made to the experiment to obtain an Rf value for this substance. [2 marks]

Edexcel question courtesy of Pearson Education Ltd.

  • The substance must be insoluble in the solvent used. [1]
  • Change the solvent to a different one that the substance does dissolve in. [1]

Sample question 3 - Higher

Question

Ethanol is a flammable liquid that boils at 78°C. It mixes completely with water, which boils at 100°C. Give a suitable method to produce a concentrated solution of ethanol from a mixture of ethanol and water. Explain a precaution to reduce the risk of harm when carrying out this separation. [3 marks]

This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.

  • Fractional distillation. [1]
  • Heat the mixture with an electric heater. [1]
  • Do not use a Bunsen burner flame as it could ignite the ethanol. [1]

Sample question 4 - Higher

Question

Copper sulfate is soluble in water but glass is not. A glass bottle of copper sulfate breaks. A student tries to produce copper sulfate crystals from the mixture of glass and copper sulfate. This is the method the student uses:

  1. Add cold water to the mixture and stir.
  2. Pour the liquid into an evaporating basin.
  3. Heat the basin with a Bunsen burner until copper sulfate crystals form.

Suggest two improvements to the student's method. [2 marks]

This question has been written by a Bitesize consultant as a suggestion to the type of question that may appear in an exam paper.

  • Use warm water at step 1. [1]
  • Use filtration at step 2. [1]