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CAIE A Level Chemistry 9701

Hydrocarbons questions

Exam-style questions on Hydrocarbons, ordered from foundation to challenge. Pick one, write your answer the way you would in the exam, and it comes back marked against the mark scheme, point by point.

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Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.

  1. Compare5 marksStandardEthene can be produced by the cracking of a long-chain alkane, for example hexane, and also by the dehydration of ethanol. Compare these two methods of producing ethene. In your answer, give the reagents and conditions…
  2. Describe5 marksStandard2-chlorobutane can be converted into an alkene by heating with sodium hydroxide dissolved in ethanol. Describe this reaction, including the type of reaction, the reagent and conditions, and the structural change that…
  3. Suggest4 marksStandardA student treats a sample of 2-methylbut-2-ene with hot concentrated acidified potassium manganate(VII). Suggest the structures of the organic products, and explain how the identity of these products allows the…
  4. Explain4 marksStandardButan-2-ol can be converted to but-2-ene by dehydration. State the reagent and conditions for this reaction, and explain why but-2-ene, rather than but-1-ene, is the major product.
  5. Explain4 marksStandardEthane reacts with chlorine in the presence of ultraviolet light to form chloroethane, C2H5Cl. Explain the mechanism of this reaction, with reference to the initiation, propagation and termination steps. Include…
  6. Explain4 marksStandardBenzene reacts with bromine in the presence of anhydrous AlBr3 to give bromobenzene. It does not readily undergo addition of bromine across the ring. Explain, in terms of the structure and stability of the benzene…
  7. Suggest4 marksStandardMethylbenzene is heated with a mixture of concentrated nitric acid and concentrated sulfuric acid at 50°C. The main organic product is a mixture of two isomeric nitro compounds. Suggest the name of the reaction type…
  8. Explain4 marksStandardA student carries out the nitration of benzene using a mixture of concentrated nitric acid and concentrated sulfuric acid at 50 °C. Explain why substitution occurs instead of addition, and describe the role of the…
  9. Explain4 marksStandardExplain why alkanes are generally unreactive towards polar reagents. Describe the conditions under which alkanes react with chlorine and give an equation for the reaction of ethane with chlorine under these conditions.
  10. Compare5 marksStandardAlkanes are generally unreactive towards polar reagents such as acids and alkalis, yet they do react with chlorine in the presence of ultraviolet light. Compare the reactivity of alkanes towards polar reagents with…
  11. Explain4 marksStandardPropene can be converted to propane by hydrogenation. Explain how this reaction is carried out, including the reagents and conditions used, and explain the role of the catalyst in the process.
  12. Explain4 marksStandardEthane reacts with chlorine in the presence of ultraviolet light to form chloroethane. Explain the mechanism of this reaction, referring to the roles of the initiation, propagation and termination steps.
  13. Describe5 marksStandardDescribe how methylbenzene is converted into benzoic acid, including the reagents and conditions required, and the role of the side-chain in this reaction.
  14. Compare5 marksStandardPropene, CH3CH=CH2, undergoes addition polymerisation to form poly(propene). Compare the structure of the propene monomer with the repeating unit of the polymer, and explain the mechanism by which the polymer is formed.
  15. Explain4 marksStandardMethylbenzene reacts with ethanoyl chloride, CH3COCl, in the presence of anhydrous aluminium chloride, AlCl3, and heat. Explain why this reaction is an example of electrophilic substitution, and why the electrophile is…
  16. Describe5 marksStandardBenzene reacts with bromine to form bromobenzene. Describe the reagents and conditions needed for this reaction, and explain why the product is formed by substitution rather than by addition of bromine to the ring.
  17. Explain4 marksStandardAn alkene with molecular formula C5H10 is treated with hot concentrated acidified potassium manganate(VII) (KMnO4). The only organic products obtained are propanone and ethanoic acid. Explain how the identities of…
  18. Compare5 marksStandardCompare the production of alkanes by the hydrogenation of alkenes and by the cracking of longer-chain alkanes. In your answer, include the reagents and conditions used in each method, and state the type of product…
  19. Compare5 marksStandardBenzene undergoes electrophilic substitution reactions such as nitration and halogenation, rather than addition reactions. Compare substitution with addition in benzene, and explain why substitution is favoured.
  20. Describe5 marksStandardDescribe how ethene is produced, and describe one reaction of ethene with each of the following reagents: hydrogen, steam, and cold dilute acidified potassium manganate(VII). State the conditions needed in each case.
  21. Suggest4 marksStandardA sample of the long-chain alkane hexadecane, C16H34, is heated with an Al2O3 catalyst in the absence of air. Suggest two alkanes and two alkenes that could be formed from the cracking of one molecule of hexadecane…
  22. Suggest4 marksStandardConcentrated sulfuric acid is a polar reagent that protonates many organic compounds. Alkanes such as hexane do not react with concentrated sulfuric acid at room temperature. Suggest why alkanes are unreactive towards…
  23. Describe5 marksStandardEthene can be converted into ethane by hydrogenation. Ethane can then undergo free-radical substitution with chlorine in the presence of ultraviolet light. Describe how ethene is converted into ethane, and describe the…
  24. Explain4 marksStandardAlkanes are generally unreactive towards polar reagents such as concentrated sulfuric acid and aqueous potassium manganate(VII). Explain this lack of reactivity in terms of the bonds present in alkane molecules.
  25. Suggest4 marksStandardA student plans to prepare cyclohexene from cyclohexanol, C6H11OH. Suggest two different sets of reagents and conditions that could be used to carry out this dehydration reaction.
  26. Compare5 marksStandardHexane, C6H14, is an alkane found in petrol. When a car engine runs, hexane undergoes combustion. Compare the complete and incomplete combustion of hexane. In your answer, refer to: the conditions under which each type…
  27. Compare5 marksStandardTwo aromatic compounds, C6H5NH2 (phenylamine) and C6H5NO2 (nitrobenzene), are each treated separately with a nitrating mixture (concentrated HNO3 and H2SO4) at 55 °C. Compare the directing effects of the amino group…
  28. Describe5 marksStandardEthane reacts with chlorine in the presence of ultraviolet light to form chloroethane. Describe the mechanism of this reaction, naming the three stages and giving an equation for each stage.
  29. Compare5 marksStandardBut-2-ene, CH3CH=CHCH3, is an alkene. It is oxidised under two different sets of conditions: cold dilute acidified KMnO4, and hot concentrated acidified KMnO4. Compare these two oxidation reactions. In your answer…
  30. Compare7 marksChallengeIn an industrial process, hexane is cracked to form a mixture that includes ethene. (a) State the conditions required for the cracking of hexane, and write an equation for the formation of ethene from hexane. (b)…
  31. Describe7 marksChallengeEthene is converted to ethanol industrially by a hydration reaction. Describe the reagents and conditions needed for this reaction, and explain the role of the catalyst. Your answer should include the type of reaction…
  32. Compare6 marksChallengeA catalytic converter is fitted to a car exhaust. The exhaust gases contain unburnt hydrocarbons, carbon monoxide and oxides of nitrogen. A student claims that the alkanes in petrol could instead be produced by…
  33. Suggest6 marksChallengeHexadecane, C16H34, is a straight-chain alkane found in the kerosene fraction of crude oil. A sample of hexadecane is heated strongly with aluminium oxide, Al2O3, in the absence of air. One of the products is octane…
  34. Suggest6 marksChallengeIn a school laboratory, a student heats cyclohexanol with concentrated phosphoric acid and collects a liquid product. The student suspects this liquid is cyclohexene. Suggest how the student could confirm that the…
  35. Explain7 marksChallengeA student carries out two experiments on separate samples of an unknown alkene, X. In experiment 1, a sample of X is warmed with cold dilute acidified aqueous KMnO4. The purple solution decolourises and a single…
  36. Explain7 marksChallengeAlkanes are generally unreactive towards polar reagents such as concentrated sulfuric acid and aqueous potassium manganate(VII), yet they react readily with chlorine in the presence of ultraviolet light. When alkanes…
  37. Describe7 marksChallengeA chemist investigates an unknown alkene, X, with the molecular formula C4H8. Treatment of X with hot concentrated acidified KMnO4 yields a single carboxylic acid. When X is reacted with HBr, a single product is…
  38. Compare7 marksChallengeA gas stove burns propane, C3H8, in a well-ventilated kitchen. A faulty stove in a poorly ventilated room may burn propane with a limited supply of air. Compare the complete and incomplete combustion of propane in…
  39. Describe7 marksChallengeAlkanes can be produced from different sources and undergo various reactions. Describe each of the following: (i) the reagents and conditions required to convert ethene into ethane by hydrogenation, (ii) how cracking…
  40. Describe5 marksChallengeEthene can be converted into ethane by hydrogenation. Describe the reagents and conditions needed for this reaction, and outline the mechanism of the free-radical substitution of ethane by chlorine in ultraviolet…
  41. Describe5 marksChallenge2-chlorobutane is heated with ethanolic sodium hydroxide. Describe the reaction that occurs, including the reagents, conditions, type of reaction, and the structure of the organic product.