OCR A Jun 2011 Paper 2 Q2

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The alcohols are an example of an homologous series. The table shows the boiling points for the first four members of straight-chain alcohols. alcohol methanol ethanol propan-1-ol butan-1-ol structural formula CH3OH CH3CH2OH CH3CH2CH2OH CH3CH2CH2CH2OH boiling point / C 65 78 97 118 (a) (i) What is the general formula of a member of the alcohol homologous series?[1] (ii) Deduce the molecular formula of the alcohol that has 13 carbon atoms per molecule.[1] (b) Alcohols contain the hydroxyl functional group. What is meant by the term functional group?[2] (c) (i) At room temperature and pressure, the first four members of the alcohol homologous series are liquids whereas the first four members of the alkanes homologous series are gases. Explain this difference.[3]OCR 2011<br /> (ii) Methylpropan-1-ol and butan-1-ol are structural isomers. Methylpropan-1-ol has a lower boiling point than butan-1-ol. Suggest why.[2] (d) Alcohols, such as methanol, can be used as fuels. (i) Write equations for the complete and incomplete combustion of methanol. complete:incomplete:[2] (ii) Suggest what conditions might lead to incomplete combustion of methanol.[1] (iii) In addition to its use as a fuel, methanol can be used as a solvent and as a petrol additive to improve combustion. State another large-scale use of methanol.[1] (e) Butan-1-ol can be oxidised by heating under reflux with excess acidified potassium dichromate(VI). Write an equation for the reaction that takes place. Use [O] to represent the oxidising agent.[2]OCR 2011 Turn over<br /> (f) Butan-1-ol is one of the structural isomers of C4H10O. (i) Write the name and draw the structure of the structural isomer of C4H10O that is a tertiary alcohol. name:structure: (ii) Draw the structure of the structural isomer of C4H10O that can be oxidised to form butanone. [2] [1] [Total: 18]OCR 2011<br />

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