Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Alkenes
106 practice questions
Topics covered
Practice questions
41–44 of 44 · Normal
Question 41
6 marks · Normal
Answer and see the solution →(a)[1 mark]Describe what is observed when bromine water is added to an alkene and the mixture is shaken.
(b)[2 marks]Write a balanced chemical equation for the reaction between but-2-ene and bromine.
(c)[1 mark]Explain why the reaction you wrote in part b is called an addition reaction.
(d)[1 mark]Describe what you would see if bromine water is added to hexane instead of but-2-ene and the mixture is shaken.
(e)[1 mark]State the difference between complete combustion and addition reactions of alkenes.
Question 42
6 marks · Normal
Answer and see the solution →(a)[2 marks]Combust ethene in air. Write the balanced symbol equation for this reaction.
(b)[2 marks]Describe in detail how you would use bromine water to distinguish between ethene and ethane.
(c)[2 marks]Explain why only one of these gases decolourises bromine water.
Question 43
6 marks · Normal
Answer and see the solution →(a)[2 marks]A student finds that a colourless, flammable liquid decolourises bromine water and burns with a smoky flame.
Explain what these two observations tell you about the type of hydrocarbon present.
(b)[2 marks]The student tests another liquid and observes that it does not decolourise bromine water and burns with a clean flame.
What type of hydrocarbon is this? Explain your reasoning.
(c)[2 marks]Write the displayed formula for but-1-ene, the alkene that would show these observations.
Question 44
6 marks · Normal
Answer and see the solution →Hex-2-ene, C6H12, is a liquid alkene. A sample is tested and burned under different conditions.
(a)[1 mark]State what is meant by an 'addition reaction' in the context of alkenes.
(b)[2 marks]Write a balanced chemical equation for the complete combustion of hex-2-ene, C6H12.
(c)[1 mark]Draw the structural formula of the compound formed when hex-2-ene reacts with bromine.
(d)[2 marks]Describe how you would test a sample of hex-2-ene using bromine water, and state the expected observation.