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CAIE A Level Chemistry 9701

Halogen compounds questions

Exam-style questions on Halogen compounds, 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 marksStandardIn a laboratory preparation, chlorine gas is bubbled through liquid benzene that contains a small amount of aluminium chloride. The mixture is warmed and chlorobenzene is produced. In a separate reaction, chloroethane…
  2. Suggest4 marksStandardA student wants to convert 1-chloropropane into a nitrile, propanenitrile, CH3CH2CN. Suggest the reagent and conditions for this conversion, and identify the mechanism by which it occurs.
  3. Explain4 marksStandardExplain why chlorobenzene is much less reactive than chloroethane in nucleophilic substitution reactions. In your answer, also describe how chlorobenzene can be prepared from benzene.
  4. Compare5 marksStandardCompare the reactivity of chloroethane and chlorobenzene towards nucleophilic substitution. In your answer, explain the difference in reactivity and describe the preparation of chlorobenzene from benzene.
  5. Explain4 marksStandardA student plans to prepare 4-chloromethylbenzene from methylbenzene using chlorine and an anhydrous aluminium chloride catalyst. (a) State the type of reaction and the condition needed for this preparation. (b) Explain…
  6. Compare5 marksStandardChloroethane and chlorobenzene both contain a chlorine atom bonded to carbon. Compare the reactivity of chloroethane with that of chlorobenzene towards nucleophilic substitution, and explain the reason for the…
  7. Explain4 marksStandardA student is given a sample of 2-chloro-2-methylpropane, (CH3)3CCl. Explain why this compound is classified as a tertiary halogenoalkane, and state the mechanism by which it is most likely to undergo nucleophilic…
  8. Explain4 marksStandardA student wants to prepare a sample of bromoethane, C2H5Br, starting from ethanol, C2H5OH. State two different reagents and conditions that could be used to carry out this conversion. For each, give the equation…
  9. Explain4 marksStandardChloroethane and chlorobenzene both contain a C–Cl bond. Explain why chloroethane reacts readily with aqueous silver nitrate to give a precipitate of silver chloride, whereas chlorobenzene does not react under the same…
  10. Suggest4 marksStandardA student wants to prepare chlorobenzene from benzene. Suggest a suitable reagent and catalyst for this reaction. In your answer, also explain why chlorobenzene is much less reactive than chloroethane towards…
  11. Compare5 marksStandard2-bromobutane is a secondary halogenoalkane. When it is heated with sodium hydroxide in ethanol, an elimination reaction occurs, producing an alkene. When it is heated with aqueous sodium hydroxide, a nucleophilic…
  12. Describe5 marksStandardChloroethane and chlorobenzene both contain a C–Cl bond. Describe the difference in reactivity between these two compounds, and explain this difference in terms of the bonding in the molecules.
  13. Compare5 marksStandardButan-2-ol reacts with hydrogen chloride gas to form 2-chlorobutane. The reaction can proceed through either an SN1 or an SN2 mechanism. Compare the SN1 and SN2 mechanisms of nucleophilic substitution in terms of the…
  14. Describe5 marksStandardEthane gas is mixed with chlorine and the mixture is exposed to ultraviolet light. A reaction takes place in which one of the hydrogen atoms of ethane is replaced by a chlorine atom. Describe the reagents and…
  15. Explain4 marksStandard2-chloro-2-methylpropane, (CH3)3CCl, is a halogenoalkane. State how this compound is classified, and explain why it is more likely to undergo nucleophilic substitution by an SN1 mechanism than by an SN2 mechanism.
  16. Explain4 marksStandard2-bromo-2-methylpropane reacts with aqueous sodium hydroxide, warmed, to form 2-methylpropan-2-ol. Explain, in terms of the mechanism, why this reaction is faster than the corresponding reaction of 1-bromopropane under…
  17. Describe5 marksStandardDescribe the difference in reactivity between chloroethane and chlorobenzene, and explain this difference in terms of the bonding in the two molecules.
  18. Explain4 marksStandard4-Chloromethylbenzene can be prepared by reacting methylbenzene with chlorine. (a) State the reagent and conditions needed for this reaction. (b) Explain why chlorobenzene is much less reactive than chloroethane…
  19. Compare5 marksStandardCompare the reactivity of chloroethane and chlorobenzene towards aqueous sodium hydroxide. In your answer, state which compound reacts and explain the difference in reactivity in terms of the bonding in the two…
  20. Compare5 marksStandard2-bromobutane is a secondary halogenoalkane. It can react with aqueous sodium hydroxide to form an alcohol, or with ethanolic sodium hydroxide to form an alkene. Compare these two reactions. In your answer, refer to…
  21. Compare5 marksStandardCompare the production of a halogenoalkane from an alcohol with its production from an alkene. In your answer, refer to the reaction of butan-2-ol with hydrogen bromide gas and to the reaction of but-1-ene with…
  22. Describe5 marksStandardBromoethane is warmed with an excess of aqueous sodium hydroxide. Describe the reaction that occurs, including the conditions, the type of mechanism, and the identity of the organic product.
  23. Suggest4 marksStandardBromoethane, C2H5Br, can be prepared by several different routes. Suggest two distinct methods for preparing bromoethane, one starting from ethene and one starting from ethanol. For each method, give the reagent(s)…
  24. Describe5 marksStandardDescribe how chloroethane can be produced from ethane by free-radical substitution, including the reagents and conditions required.
  25. Describe5 marksStandardBromoethane is warmed with an excess of aqueous sodium hydroxide. Describe what happens in this reaction, including the conditions, the type of reaction, the organic product formed, and the identity of the nucleophile.
  26. Suggest4 marksStandardSuggest the reagents and conditions needed to convert ethene into 1,2-dibromoethane. Explain the type of reaction involved.
  27. Explain4 marksStandardChloroethane and chlorobenzene both contain a chlorine atom bonded to a carbon atom. Explain why chloroethane reacts readily with aqueous sodium hydroxide, whereas chlorobenzene does not react with aqueous sodium…
  28. Explain4 marksStandardExplain why primary halogenoalkanes tend to undergo nucleophilic substitution via an SN2 mechanism, whereas tertiary halogenoalkanes tend to undergo nucleophilic substitution via an SN1 mechanism. In your answer, refer…
  29. Compare5 marksStandardChloroethane and chlorobenzene are both halogeno compounds. A student adds aqueous silver nitrate to separate samples of each compound and warms the mixtures. The student observes that chloroethane reacts readily…
  30. Suggest6 marksChallengeChloroethane reacts readily with aqueous sodium hydroxide to form ethanol. Chlorobenzene does not react with aqueous sodium hydroxide under the same conditions. Suggest why chlorobenzene is much less reactive than…
  31. Explain5 marksChallenge2-bromo-2-methylpropane reacts with aqueous sodium hydroxide to form 2-methylpropan-2-ol. Explain the mechanism of this reaction, including the inductive effect of the alkyl groups and the reason for the stability of…
  32. Describe6 marksChallengeA student plans to prepare chlorobenzene from benzene and then compare its reactivity with chloroethane. (a) Describe how the student could prepare chlorobenzene from benzene, naming the reagent(s) and catalyst. (b)…
  33. Explain7 marksChallenge2-bromo-2-methylpropane, (CH3)3CBr, is a tertiary halogenoalkane. A student adds a few drops of aqueous silver nitrate, AgNO3(aq), in ethanol to a sample of 2-bromo-2-methylpropane and warms the mixture. A precipitate…
  34. Describe7 marksChallengeDescribe the mechanisms of nucleophilic substitution in halogenoalkanes. In your answer, explain how the structure (primary, secondary, tertiary) of the halogenoalkane determines which mechanism predominates and the…
  35. Describe7 marksChallengeBromoethane is a primary halogenoalkane. It reacts with aqueous sodium hydroxide on warming to form ethanol. Describe the reaction of bromoethane with aqueous sodium hydroxide, including the reagents and conditions…
  36. Describe7 marksChallengeDescribe a laboratory preparation of chlorobenzene from benzene, including essential reagents and conditions. Also describe how methylbenzene reacts under similar conditions. Then explain why chlorobenzene is less…
  37. Explain6 marksChallenge2-chloro-2-methylpropane reacts with aqueous sodium hydroxide to form 2-methylpropan-2-ol. Explain, with reference to the structure of the halogenoalkane, why this reaction proceeds by an SN1 mechanism rather than SN2.
  38. Suggest6 marksChallenge1-chloropropane reacts with potassium cyanide dissolved in ethanol, with heat, to form a nitrile. Suggest, in terms of the reaction type and the role of the cyanide ion, why this reaction is useful in organic…
  39. Describe6 marksChallengeEthane gas is mixed with chlorine gas in a sealed tube and exposed to ultraviolet light. A mixture of products is obtained, including chloroethane and a compound of formula C2H4Cl2. Describe the mechanism of this…
  40. Compare6 marksChallenge2-bromobutane is a secondary halogenoalkane. When it is heated with aqueous sodium hydroxide, the product is butan-2-ol. When it is heated with sodium hydroxide dissolved in ethanol, the product is a mixture of two…
  41. Compare7 marksChallengeChlorobenzene and chloroethane are both organic compounds containing a chlorine atom bonded to carbon. (a) State the reagents and conditions needed to prepare chlorobenzene from benzene. (b) Methylbenzene can also be…
  42. Compare7 marksChallenge2-bromobutane is a secondary halogenoalkane. When it is heated with ethanolic sodium hydroxide, elimination competes with nucleophilic substitution. Compare these two reactions in terms of the reagent and conditions…
  43. Suggest5 marksChallengeA student has a sample of 1-chloropropane and wants to convert it first into a nitrile and then into a primary amine. Suggest the reagent(s) and conditions for each step, and name the type of mechanism involved in each…