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 are no core practical activities in the Fuels and Earth science section.

Sample question 1 - Foundation

Question

Some impurities in hydrocarbon fuels result in the production of sulfur dioxide gas, SO2.

A teacher demonstrates the combustion of sulfur. A small amount of sulfur powder is burned in a gas jar of oxygen. Water is then added to the gas jar, which is then shaken to mix dissolve the sulfur dioxide.

a) Write a balanced equation to show the reaction between sulfur and oxygen, O2.[1 mark]

b) State what is observed when some universal indicator solution is added to the mixture in the gas jar. Explain your answer. [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.

  • a) S + O2 → SO2 [1]
  • b) Observation [1] with reason [1], eg:
    • indicator turns red/orange/yellow
    • sulfur dioxide dissolves to form an acidic solution/an acid forms
    • conical flask

Sample question 2 - Foundation

Question

Oxygen is released by plants during photosynthesis.

Describe the chemical test for oxygen. [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.

  • glowing splint/smouldering splint [1]
  • relights [1]

Sample question 3 - Higher

Question

A student carried out an experiment to prove that candle wax, a hydrocarbon, produces carbon dioxide and water vapour when it burns. The equipment used is shown in the diagram.

Candle heat is carried through a tube into limewater. Another tube carries air from the limewater tube into a boiling tube in a beaker of ice and water, before a final tube continues to a pump.

The gas produced from the burning candle is drawn through the apparatus.

The limewater turned milky showing that carbon dioxide had been formed.

A small amount of a colourless liquid condensed in boiling tube X. The student claimed that this proved that burning candle wax produced water.

The teacher said the apparatus had been set up incorrectly and therefore this conclusion about water was not valid.

Explain how the student could modify the equipment to prove that water is produced by burning candle wax.

[2 marks]

Edexcel question courtesy of Pearson Education Ltd.

  • reverse the boiling tubes/pass gas through the tube in ice water first [1]
  • so that if any liquid condenses in the tube, it must have come from the burning wax (and not from the limewater) [1]

Sample question 4 - Higher

Question

Fractions of crude oil contain alkanes.

A sample of decane, C10H22, was cracked using the apparatus shown in the diagram.

This produced a mixture of products, including ethene.

Two bunsen burners heat ceramic wool in decane and porous pot, in a test tube. The air is passed through a tube into an upturned test tube containing water.

Explain how ethene is produced using the apparatus shown in the diagram. [3 marks]

Edexcel question courtesy of Pearson Education Ltd.

  • when the decane is heated it vaporises/turns to a gas [1]
  • decane vapour/gas breaks down as it comes in contact with the catalyst (hot porous pot) [1]
  • large molecules of decane produce smaller molecules, including ethene [1]