1. 1
   A petrochemical company chemist is analysing a series of hydrocarbon samples extracted from natural gas, identifying their molecular formulae and classifying them into families based on shared characteristics, before naming individual compounds according to IUPAC rules.

   (a)

   A petrochemical company analyses a sample of natural gas and finds it consists entirely of molecules made only from carbon and hydrogen atoms. What term describes this type of compound?

   [1 mark]

   • ACarbohydrate
   • BHydrocarbon
   • CHydroxide
   • DCarbonate

   (b)

   The chemist notices that several of the hydrocarbons analysed share the same general formula and similar chemical properties, differing only by additional CH2 units between members. What term describes such a family of compounds?

   [1 mark]

   • AIsomer set
   • BEmpirical family
   • CFunctional group
   • DHomologous series

   (c)

   Explain what is meant by the term functional group, and explain what is meant by the term isomerism, using an example from the chemist's hydrocarbon analysis to illustrate isomerism.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A patent examiner is reviewing a chemical patent application describing a newly synthesised organic compound, and must check that the compound has been correctly named using IUPAC nomenclature and correctly represented using structural and displayed formulae before the patent can be approved.

   (a)

   The compound's main chain contains three carbon atoms. Which prefix indicates a three-carbon chain in IUPAC naming?

   [1 mark]

   • AMeth-
   • BEth-
   • CProp-
   • DBut-

   (b)

   The patent describes the compound's reaction with bromine, in which a bromine atom directly replaces a hydrogen atom on the carbon chain, with no atoms being added overall. How should this type of reaction be classified?

   [1 mark]

   • ASubstitution
   • BCombustion
   • CAddition
   • DNeutralisation

   (c)

   Explain the difference between a structural formula and a displayed formula for an organic molecule, using a compound with the molecular formula C3H8 as an example.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A materials science student is comparing two unlabelled hydrocarbon samples given to them in a laboratory class, one described as saturated and the other as unsaturated, and must use chemical tests and formula analysis to identify and distinguish between the two samples before writing up a laboratory report.

   (a)

   A materials science student is comparing two unlabelled organic samples, both hydrocarbons, one classified as saturated and the other as unsaturated. Explain how the general formula and the type of bonding differ between a saturated hydrocarbon and an unsaturated hydrocarbon.

   [3 marks]

   (b)

   Describe a chemical test the student could use to distinguish between the saturated hydrocarbon sample and the unsaturated hydrocarbon sample, stating what would be observed with each.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A chemistry textbook author is preparing a worked example for a new edition, explaining to students how to systematically derive all possible structural and displayed formulae for an organic compound given only its molecular formula, using the four-carbon alkane C4H10 as the central example throughout the explanation.

   (a)

   A textbook author is writing a chapter explaining how to derive possible structures for an organic compound from its molecular formula alone. Using the molecular formula C4H10 as a worked example, describe, in full detail, how a student could systematically work out all the possible structural and displayed formulae for compounds with this molecular formula, and explain how these compounds relate to each other in terms of isomerism.

   [6 marks]

   (b)

   The textbook author wants to extend the worked example to explain why classifying a reaction as substitution, addition or combustion depends on the type of hydrocarbon and reagent involved. Using the four-carbon alkane and a four-carbon alkene as examples, explain and evaluate how each of these two hydrocarbons would react differently with bromine, and how each would react with oxygen, classifying each reaction type and explaining the reasoning.

   [6 marks]

   Total for question 4: 12 marks

End of questions