1. 1
   A school chemistry class is comparing samples of different organic compounds sent from a laboratory. Each sample is labelled only with its molecular formula, and the students must work out which homologous series each compound belongs to before carrying out further tests.

   (a)

   A student is told that a molecule has the molecular formula C4H10. Which general formula does this molecule belong to?

   [1 mark]

   • ACnH2n+2 (alkane)
   • BCnH2n (alkene)
   • CCnH2n+1OH (alcohol)
   • DCnH2n+1COOH (carboxylic acid)

   (b)

   One sample sent to the class has the molecular formula C3H6. To which homologous series does this compound belong?

   [1 mark]

   • AAlkane
   • BAlkene
   • CAlcohol
   • DCarboxylic acid

   (c)

   State two features that all members of the same homologous series have in common.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A perfume manufacturer produces a fragrance compound by reacting ethanol with ethanoic acid to form an ester with a fruity smell. The manufacturer needs to confirm the structure and naming of each compound involved before scaling up production.

   (a)

   A perfume manufacturer uses an ester made from ethanol and ethanoic acid. Which functional group is responsible for the chemical properties of ethanol?

   [1 mark]

   • AC=C
   • B-COOH
   • C-OH
   • D-COO-

   (b)

   Ethanoic acid and ethanol both have the molecular formula-based name ending in a suffix that identifies their homologous series. Which pair of endings correctly identifies ethanoic acid and ethanol?

   [1 mark]

   • A-ol and -ane
   • B-ol and -oic acid
   • C-ane and -ene
   • D-oic acid and -ol

   (c)

   (i) Give the structural formula of the ester made from ethanol and ethanoic acid. (ii) Explain, in terms of atoms and bonds, what a structural formula shows about a molecule.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A food scientist studying historical methods of alcohol production is comparing two four-carbon alcohols, butan-1-ol and butan-2-ol, which have both traditionally been used as flavourings in the food industry.

   (a)

   Explain what is meant by the term structural isomers, and state the relationship between butan-1-ol and butan-2-ol. Give the molecular formula shared by both alcohols, and explain how you worked it out from the general formula for alcohols.

   [3 marks]

   (b)

   (a) Draw out, in words, the displayed formula of propan-1-ol, describing every atom and bond present. (b) State whether propan-1-ol is saturated or unsaturated, and explain what this term means.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A materials laboratory receives an unlabelled organic sample from a manufacturer and must identify which homologous series it belongs to using only chemical tests and formulae, without being given the compound's name or any diagram of its structure.

   (a)

   A materials laboratory receives an unlabelled sample and, from tests, confirms it contains carbon-carbon double bonds and fits the general formula CnH2n. Explain how the laboratory could conclude the compound belongs to the alkene homologous series, describing the meaning of a functional group, a homologous series, and the terms saturated and unsaturated as applied to this sample.

   [6 marks]

   (b)

   The laboratory also receives a second unlabelled sample that turns out to be but-2-ene. Explain what is meant by the terms molecular formula and displayed formula, give the molecular formula of but-2-ene, describe in words its displayed formula, and explain why but-1-ene and but-2-ene are considered structural isomers of each other.

   [6 marks]

   Total for question 4: 12 marks

End of questions