1. 1
   Ethyl butanoate is used as a pineapple flavouring in sweets. Its condensed structural formula is CH₃CH₂CH₂COOCH₂CH₃.

   (a)

   What is the molecular formula of ethyl butanoate?

   [1 mark]

   • AC₆H₁₂O₂
   • BC₃H₆O
   • CC₆H₁₀O₂
   • DC₅H₁₂O₂

   (b)

   Which functional group is present in ethyl butanoate?

   [1 mark]

   • ACarboxyl
   • BEster
   • CHydroxyl
   • DAmido

   (c)

   Deduce the empirical formula of ethyl butanoate and explain how it is related to the molecular formula.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Gas chromatography of an industrial solvent shows it contains four compounds, all with the molecular formula C₄H₁₀O: butan-1-ol (CH₃CH₂CH₂CH₂OH), butan-2-ol (CH₃CH(OH)CH₂CH₃), a compound with the condensed formula (CH₃)₂CHCH₂OH, and ethoxyethane (CH₃CH₂OCH₂CH₃).

   (a)

   What is the IUPAC name of (CH₃)₂CHCH₂OH?

   [1 mark]

   • AButan-2-ol
   • B2-methylpropan-2-ol
   • C2-methylpropan-1-ol
   • D2-methylbutan-1-ol

   (b)

   Which pair of compounds are functional group isomers?

   [1 mark]

   • AButan-1-ol and butan-2-ol
   • BButan-1-ol and (CH₃)₂CHCH₂OH
   • CButan-1-ol and butanal
   • DButan-1-ol and ethoxyethane

   (c)

   Explain why butan-1-ol and butan-2-ol are structural isomers, and state the type of structural isomerism they show.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   The boiling points of the first five straight-chain alcohols are: methanol (Mr 32) 65 °C, ethanol (Mr 46) 78 °C, propan-1-ol (Mr 60) 97 °C, butan-1-ol (Mr 74) 117 °C and pentan-1-ol (Mr 88) 138 °C. The boiling points of the alkanes with the closest molar masses are: ethane (Mr 30) −89 °C, propane (Mr 44) −42 °C, butane (Mr 58) −1 °C, pentane (Mr 72) 36 °C and hexane (Mr 86) 69 °C.

   (a)

   State the general formula of the alcohols and explain the trend in boiling point from methanol to pentan-1-ol.

   [3 marks]

   (b)

   A student claims that 'the difference between the boiling point of an alcohol and that of the alkane of similar molar mass becomes smaller as the chain length increases'. Evaluate this claim using the data, explaining the difference between ethanol and propane.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A fragrance chemist has four unlabelled compounds, each with three carbon atoms in its molecules. P, C₃H₆O₂, dissolves in water to give an acidic solution. Q, also C₃H₆O₂, is neutral and has a fruity smell. R, C₃H₆O, has a carbonyl group on the second carbon atom of an unbranched chain. S, also C₃H₆O, has a carbonyl group on the first carbon atom of an unbranched chain.

   (a)

   Deduce the condensed structural formula and IUPAC name of P, R and S, identifying the functional group and homologous series of each.

   [6 marks]

   (b)

   Deduce two possible structures and names for Q. Classify the type of isomerism shown by P and Q and by R and S, and predict and explain whether P or Q has the higher boiling point.

   [6 marks]

   Total for question 4: 12 marks

End of questions