WJEC A Level Chemistry
WJEC A Level Chemistry 2.5 Hydrocarbons Exam Questions
Free WJEC A Level Chemistry exam questions on 2.5 Hydrocarbons, with mark schemes. Covers alkanes, radical substitution, alkenes, electrophilic addition and polymers.
2.5 Hydrocarbons exam questions
1 question pack of real past exam questions with its mark scheme. Answer every question without notes, then mark your answers line by line against the mark scheme.
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WJEC A Level Chemistry Flashcards (Anki & Quizlet)
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Use them on Anki or Quizlet, then test yourself with the questions on this page.
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About WJEC A Level Chemistry 2.5 Hydrocarbons
This topic covers the reactions of alkanes and alkenes. Mechanism questions are common.
What you need to know
- Alkanes Combustion and free radical substitution with initiation, propagation and termination.
- Alkenes Electrophilic addition of HBr, Br₂ and H₂O, with curly arrows and carbocations.
- Markovnikov The more stable carbocation leads to the major product.
- Polymers Addition polymerisation and disposal of polymers.
Common mistakes in 2.5 Hydrocarbons
- Drawing curly arrows from the wrong place.
- Missing the carbocation intermediate.
- Forgetting UV light in radical substitution.
Try three 2.5 Hydrocarbons exam-style questions
1. State the conditions for the reaction of methane with chlorine. (1 mark)
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UV light.
2. Describe the test for an alkene. (1 mark)
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Bromine water decolourises from orange to colourless.
3. Explain why propene and HBr give mainly 2-bromopropane. (2 marks)
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The secondary carbocation is more stable (1) because of more alkyl groups donating electrons (1).
2.5 Hydrocarbons FAQs
What does Hydrocarbons cover?
Reactions of alkanes and alkenes and addition polymers.
Do I need mechanisms?
Yes, radical substitution and electrophilic addition.
How are polymers disposed of?
Landfill, incineration, recycling and use as feedstock, each with issues.
Revise this topic with flashcards: WJEC A Level Chemistry Flashcards, with mark scheme answers for Anki and Quizlet.
