Chlorination of alkanesAQA A-Level Chemistry: Flashcards
What these 13 flashcards ask
- What conditions does the reaction of methane with chlorine need?
- What is a radical?
- What is homolytic fission?
- Write the initiation step for methane and chlorine.
- Write the first propagation step.
- Write the second propagation step.
- Why is the second propagation step important for the chain reaction?
- What happens in a termination step?
- Give a termination step that forms ethane.
- Give a termination step that forms chloromethane.
- Name the type of mechanism in alkane chlorination.
- Why are several products formed in chlorination of methane?
- How can multiple substitution be reduced?
Exam questions on Chlorination of alkanes
- Methane reacts with chlorine in the presence of ultraviolet light to form chloromethane, CH₃Cl, and hydrogen chloride. The reaction takes place by a free-radical substitution mechanism.Explain why ultraviolet light is needed for the initiation step.2 marks
- When methane reacts with chlorine in ultraviolet light, the product mixture also contains small amounts of ethane, C₂H₆, and dichloromethane, CH₂Cl₂.Write equations for the two propagation steps that convert chloromethane, CH₃Cl, into dichloromethane, CH₂Cl₂.2 marks
- Ethane, CH₃CH₃, reacts with chlorine in the presence of ultraviolet light to form chloroethane, CH₃CH₂Cl, by the same type of mechanism as the reaction of methane with chlorine.Write equations for the initiation step and the two propagation steps in this reaction.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).