Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
The combustion of elements in oxygen
18 practice questions
Practice questions
1–8 of 8 · Normal
Question 1
2 marks · Normal
Answer and see the solution →State what is meant by a combustion reaction. Give an example of a combustion reaction involving an element.
Question 2
4 marks · Normal
Answer and see the solution →The diagram shows an experiment in which a piece of magnesium ribbon is burned in a bell jar containing air, floating on water as described.
(a)[1 mark]State what you would observe when magnesium burns in the air inside the bell jar.
(b)[1 mark]Write a word equation for the combustion of magnesium in oxygen.
(c)[2 marks]Explain why the level of water rises inside the bell jar after the reaction.
Question 3
1 mark · Normal
Answer and check →Which of the following best describes what happens when an element combusts in oxygen?
- A.A new compound is formed and energy is released.
- B.The element turns into a gas without reacting.
- C.The element dissolves in oxygen.
- D.No change takes place.
Question 4
2 marks · Normal
Answer and see the solution →Suggest one reason why some elements burn more brightly in pure oxygen than in air. Name an element that burns brightly in oxygen.
Question 5
4 marks · Normal
Answer and see the solution →Sulfur burns in oxygen to make a new substance.
(a)[1 mark]Describe what you would see when sulfur is burned in oxygen.
(b)[1 mark]Write a balanced chemical equation for the reaction between sulfur and oxygen.
(c)[1 mark]Name the product formed.
(d)[1 mark]Briefly explain why burning sulfur in oxygen is a combustion reaction.
Question 6
3 marks · Normal
Answer and see the solution →When magnesium burns in oxygen, it forms magnesium oxide. Student A burns 1.2 g of magnesium in excess oxygen. The equation is:
Calculate the mass of magnesium oxide formed. (Relative atomic masses: Mg = 24, O = 16)
Question 7
3 marks · Normal
Answer and see the solution →Sodium burns with a bright yellow flame when heated in oxygen. Explain, with reference to the reaction, why the flame is brighter and the reaction is faster when sodium is heated in pure oxygen, compared to heating it in air.
Question 8
4 marks · Normal
Answer and see the solution →The diagram below shows a scientist burning a piece of magnesium in a bell jar filled with air. The bell jar is placed over a trough of water. After ignition, the magnesium burns in oxygen to form magnesium oxide.
Burning magnesium in a bell jar over water. Measured water volumes used to fill the bell jar to marked levels before and after reaction. Water level Volume / cm³ Initial 695 Final 830 After burning, the white magnesium oxide forms and dissolves in the water. The levels of water inside the bell jar before and after combustion are shown in the table.
(a)[1 mark]State one observation you would see when magnesium reacts with oxygen in this experiment.
(b)[1 mark]Calculate the volume of oxygen that was used up during the reaction. Show your working.
(c)[1 mark]Given that the total volume of air in the bell jar at the start was 695 cm³, calculate the percentage of oxygen in the air based on your answer to (b). Show your answer to two significant figures.
(d)[1 mark]Explain why there might still be some magnesium left after the experiment.